A juvenile, as petitioner, on July 2,1979, applied to a single justice of this court to use the court’s supervisory powers, G. L. c. 211, § 3, to stay his trial in the Superior Court, county of Suffolk, set to begin that day, on charges of raping a child under the age of sixteen (G. L. *553c. 265, § 22A). He contended that the trial would be unlawful and ultimately futile because of certain infirmities in the procedure by which his case was ordered transferred from the Boston Juvenile Court to the Superior Court, to be handled there as if the petitioner were an adult (G. L. c. 119, § 61); he contended also that the trial should be aborted because he had been denied his constitutional right to a speedy trial. As relief (although not specifically stated in his application) he sought dismissal of the indictment and a decision that he was free of any form of prosecution for the alleged incident of rape. The single justice stayed further proceedings in the Superior Court and, after the parties had settled a statement of agreed facts, reserved and reported the matter to the full court.
From the statement of facts we learn the following. On May 7,1976, the petitioner was complained of in the Boston Juvenile Court for delinquency, in that on May 1, 1976, he had forced sexual intercourse upon a child under sixteen.2 The petitioner was then in the fourteen-to-seventeen year class — he was sixteen years, five months old, having been born on December 16, 1959. On motion for transfer to the Superior Court, the first part of the transfer process — an inquiry into probable cause — was conducted on June 30, 1976. There was testimony tending to prove that the petitioner on May 1, 1976, had raped the victim, a girl five years old, at knife-point, and left her bleeding in a hallway. The special justice found that probable cause existed.
On July 14, 1976, a hearing was held on the question of transfer. In the interim clinical evaluations of the petitioner had been made on the justice’s order. Received at the hearing were reports from the court clinic psychiatrist, the probation department, the Department of Youth Services (DYS), and the Boston Juvenile Court clinic. The justice heard from the petitioner’s mother, two family friends, and *554the director of a METCO program in which the petitioner was participating. Finally there was testimony from the person (and her supervisor) responsible for court liaison with DYS. On July 28, 1976, the justice entered his findings and order, stated to be on clear and convincing evidence, with the findings that “the [petitioner] poses a serious threat to the public” and that he “cannot be rehabilitated within the juvenile justice system.” (The text of the findings and order appears herein at n.10 and will be discussed below.)
Accordingly, the juvenile complaint was dismissed and a criminal complaint issued, and on September 13, 1976, the grand jury found an indictment under G. L. c. 265, § 22A, to which, on arraignment November 9, 1976, the petitioner pleaded not guilty. On November 29, 1976, the petitioner moved (with a formal affidavit) in Superior Court to dismiss the indictment under G. L. c. 277, § 47A, on the ground that the “opinion and order” of transfer violated the standards announced in A Juvenile v. Commonwealth, 370 Mass. 272 (1976).
The motion was not heard until August 9, 1977. On September 8, 1977, a judge of the Superior Court issued his “findings and order” stating that the transfer order had inadequate subsidiary findings, and “remanding” the case to the Boston Juvenile Court for the inclusion of subsidiary findings.
This Superior Court order reached the Boston Juvenile Court but was not acted on. On December 4, 1978, the petitioner filed a second or renewed motion to dismiss the indictment, pointing out that fourteen months had elapsed since the remand. The motion came on before a second Superior Court judge who on December 21, 1978, directed the parties to get in touch with the Juvenile Court special justice who had made the transfer order. The assistant district attorney wrote to the justice on January 12, 1979. That justice on February 14, 1979, issued findings and order similar to those of July 28, 1976, except for an addendum to the sixth subsidiary finding (see n.14 below). More delay occurred because of an omission to send a copy of the Febru*555ary 14 paper to the petitioner’s attorney. As soon as the attorney learned of it, he on May 10, 1979, filed in Superior Court a motion to suppress the further finding. He contended that, as the original juvenile complaint was dismissed pursuant to G. L. c. 119, § 61, when the transfer order was made, there was nothing on which a further finding could attach. After hearing on the motion to suppress as well as the two motions to dismiss the indictment, another judge of the Superior Court denied all three motions, and set the trial for July 2, 1979. (It is stipulated that both sides have been ready for trial since August 9, 1977, the date of remand.) The judge declined to report the case to this court pursuant to G. L. c. 278, § 30A (since repealed; see now Mass. R. Crim. P. 34, 378 Mass. 905 [1979]). As noted above, application to the single justice was made on July 2, 1979.
Questions are put to us about the appropriateness of invoking this court’s supervisory power in the present circumstances; the correctness of the ruling denying the motions to dismiss the indictments which had attacked the underlying transfer orders; and the claim of deprivation of speedy trial. We shall hold: (1) The case is a proper one for consideration under G. L. c. 211, § 3. (2) Both the original and supplemental findings of the Juvenile Court were insufficient by reason of gross ambiguity to support a transfer order. That court should be given a further- opportunity to attempt to correct the findings. (3) Especially in the light of this disposition, the question of speedy trial may be passed over.
1. Short of persuading the judge of the Superior Court to report to an appellate court his denial of the motions to dismiss the indictment, the petitioner had no immediate means in the normal course of getting that order reviewed: it was interlocutory in character, and not within G. L. c. 278, § 28E, which, in the converse situation of an order allowing a motion to dismiss an indictment, grants the Commonwealth a right of appeal. (See also Mass. R. Crim. P. 15 [b] [1], 378 Mass. 883 [1979].) Hence the petitioner’s resort to our supervisory power. On the petitioner’s view, *556he should be spared the expense and anxiety of a trial because a conviction would ultimately have to be upset without further recourse by the Commonwealth against him. That prospect, standing alone, might not suffice to justify an exercise of the § 3 power. Cf. A Juvenile v. Commonwealth, 375 Mass. 104, 106 (1978); Commonwealth v. Cavanaugh, 366 Mass. 277, 279 (1974). Here, however, we have a question of proper transfer practice, involving the working relation between two departments of the Trial Court. This calls peculiarly for supervision and settlement by us, and should not await some fortuitous opportunity of report or ordinary appeal. See A Juvenile v. Commonwealth, 370 Mass. 272, 273 (1976); County Comm’rs of the County of Bristol v. Judges of Probate of the County of Bristol, 338 Mass. 738 (1959). The single justice thought a § 3 proceeding appropriate (he pointed out that the case raised issues said to be common to other cases involving proceedings against juveniles). We agree.
2. “In a criminal case, any defense or objection based upon defects in the institution of the prosecution or in the complaint or indictment” including “a failure to show jurisdiction in the court or to charge an offense” may be raised by motion under G. L. c. 277, § 47A, and it was under that section that the petitioner made his motion and renewed motion to dismiss the indictment herein.3 We have the question of the extent to which a judge of the Superior Court (or finally this court) may go behind an indictment valid on its face to reach an antecedent error committed in the proceedings in a Juvenile Court.
It should be accepted that judges of the Superior Court do not sit as appellate tribunals to review de novo the soundness of decisions made by Juvenile'Court judges to dismiss *557particular delinquency complaints.4 And in the present case the petitioner did not seek by his motions to attack the nature or extent of the proof received by the Juvenile Court in the transfer proceeding.5
But it seems not only proper for the Superior Court judges, but obligatory upon them, when a § 47A motion is addressed to the point, to consider whether there has been a material failing in the prescribed steps leading to the issuance of the order of transfer. (Section 47A, as noted, speaks of “defects in the institution of the prosecution.”) Our cases indicate that this scrutiny is surely in order for procedure at the Juvenile Court level that may be offensive to the Constitution (although we have not found such a “defect” in the cases that have reached us). See Stokes v. Commonwealth, 368 Mass. 754, 764, 774-776 (1975) (doctrine of Breed v. Jones), habeas corpus denied sub nom. Stokes v. Fair, 581 F.2d 287 (1st Cir. 1978); Commonwealth v. Roberts, 362 Mass. 357, 369 (1972) (written findings not constitutionally required). Such scrutiny likewise applies to material error short of the constitutional. See Connaughton v. District Court of Chelsea, 371 Mass. 301 (1976) (denial of juvenile’s right to bring in stenographer); A Juvenile, petitioner, 364 Mass. 531, 538-539, 541 (1974) (failure to afford separate hearing as to dismissal of juvenile complaint, and other procedural difficulties); Commonwealth v. A Juvenile, 363 Mass. 640 (1973) (combination of procedural actions by judge in Juvenile Court incompatible with “proper administration of criminal justice”). We have indicated that judges *558of the Superior Court may deal with such defects by dismissal of indictments — which in some cases could be followed by reinstitution of proceedings in the Juvenile Court, see A Juvenile v. Commonwealth, 375 Mass. 104 (1978) — or by remittal to the Juvenile Court for correction. See Connaughton, supra at 302 (application under G. L. c. 211, § 3, not appropriate because Superior Court could provide any one of a number of remedies, including dismissal of the indictment, or an order for additional proceedings in Juvenile Court); Commonwealth v. A Juvenile, supra, 363 Mass. at 642 (Superior Court could be applied to, to dismiss indictment) . Such defects can also be searched out by us after trial and conviction on the criminal complaint, and we may require reference back to the Juvenile Court for further proceedings. See A Juvenile, petitioner, supra, 364 Mass. at 544.
Serious deficiency in the subsidiary findings should count as a faulty step in the process of transfer, examinable as above indicated.6 A resume of the present procedure for transfer shows those findings to be of vital significance. By G. L. c. 119, § 61, where a delinquency complaint alleges that a child between the ages of fourteen and seventeen has committed “an offense involving the infliction or threat of serious bodily harm,”7 the Juvenile Court, after a hearing and finding of probable cause, shall go on to consider evidence of five factors (among others that may be relevant): “(a) the seriousness of the alleged offense; (b) the child’s *559family, school and social history, including his court and juvenile delinquency record, if any; (c) adequate protection of the public, (d) the nature of any past treatment efforts for the child, and (e) the likelihood of rehabilitation of the child.” The court may decide to continue to treat the child as a delinquent. But it may dismiss the juvenile complaint and issue a criminal complaint if, on “clear and convincing evidence,” it makes a “written finding” that the child “[i] presents a significant dánger to the public as demonstrated by the nature of the offense charged and the child’s past record of delinquent behavior, if any, and [ii] is not amenable to rehabilitation as a juvenile.” In the important case of A Juvenile v. Commonwealth, 370 Mass. 272 (1976), the court interpreted and supplemented § 61 by “ Guidelines for Transfer Hearings.” Id. at 280-283.
We first stressed “the important consequences that result from a transfer decision” (id. at 281), as shown by comparing juvenile treatment with that accorded an adult for like misbehavior. We spoke of “the legislative policy underlying our statutes relating to delinquent children” (id.), concluding that “the Legislature intended that noncriminal treatment is to be favored and that transfer should be ordered only when warranted by exceptional circumstances” (id. at 281-282), but still leaving the judge with a range of discretion in appraising the factors mentioned in § 61,8 with “no specific requirement that [he] weigh these factors in a certain manner or achieve some predesigned balance.” Id. at 282.
More specifically, we said we did not believe a decision to transfer was proper “when supported by findings which deal only with the seriousness of the charge and the inadequacy of existing juvenile facilities in terms of safeguarding the public.” Id. at 282. “[T]here must also be a finding that the juvenile cannot be rehabilitated within the present juvenile structure, or that, in the absence of long-term su*560pervision and security, he poses a serious threat to the public . . . .” Id. There must be “subsidiary findings indicating the basis for this conclusion.” Id. 9
In the present case there is no claim that the Juvenile Court failed to receive evidence about or “consider” the five factors, and no assault is made on the conclusory statutory finding about danger to the public. In the arguments all turns on the question of support for the additional necessary finding of nonamenability of the present petitioner to rehabilitation, and here we are bound to agree with the petitioner that the findings and order of July 28, 1976,10 contained insufficient subsidiary findings. What appeared on the matter in the findings was ambiguous and seemed to commit the very mistake of resting on the seriousness of the charge and inadequacy of facilities to safeguard the public (“Théir facilities [DYS] are semi-secure, at best”).
*561As to the crucial question of rehabilitation: There were findings that the petitioner had no prior delinquency record; that he was a high school student living with his parents and siblings in a family that was “well intact”; that the report of the court clinic indicated there was no need for psychiatric recommendations for the petitioner; and that DYS had no recommendation for him. These facts and reports suggested a good prognosis for a first offender (unless, indeed, the reports were to be read as meaning that the agencies were simply baffled by the petitioner’s singular incident of assumed misconduct, and were therefore resigned to passing the petitioner to the criminal process).* 11 The findings then went on to say that “ [confinement in any of their [DYS] facilities would be for four months.” This statement (unexplained) might have appeared to go not to rehabilitation but to the question of protection of the public; in its possible bearing on rehabilitation, it suggested that more than four months’ confinement was needed for a sound rehabilitative program. There was a further statement that “[t]hey [DYS] offer no treatment for sexual offenders.” But the latter two quoted findings were not tied back to, or reconciled with, the earlier affirmative or hopeful indications. The upshot, as we have said, was ambiguity. We should *562add that while the petitioner’s age was given — a year and a half left to the limiting age of eighteen — this time factor was not brought into the assessment.12
The judge of the Superior Court in his order of September 8, 1977, “remanding”13 the case to the Juvenile Court “to include subsidiary findings,” did not describe the ground of his discontent, and when, after long delay, the judge of the Juvenile Court responded, it was with an insignificant or repetitious addendum.14 In denying the petitioner’s second motion to dismiss the indictment, the Superior Court judge overlooked the unrepaired ambiguities in the findings. Possibly he thought himself faced with a choice between, on the one hand, dismissing the indictment with no chance of reinstitution of proceedings in the Juvenile Court (the petitioner being now more than eighteen years old) or of reindictment (G. L. c. 119, § 74), and, on the other hand, retaining the indictment despite its infirmities — and he chose the latter course.15 We do not agree with either extreme and think there is a better, although still an imperfect, alternative as follows: The indictment may remain in place provisionally. We shall direct the Superior Court to request the Juvenile Court, on the basis of the record already made, to clarify its last findings and order of February 14, 1979, in the light of the “Guidelines” and the present opinion. The steps are to be carried out promptly. If it *563should appear from revised findings that a case for transfer was not made, the petitioner will be entitled on motion in the Superior Court to a dismissal of the indictment; if adequate revised findings indicate otherwise, the indictment will stand and the case will proceed to trial.16
This is not to be understood as a reinstitution of juvenile proceedings out of time, but as a chance for the Juvenile Court to restate and improve ambiguous findings. There is plenty of precedent for nunc pro tunc reconsideration, even after the child has become adult, to improve a transfer order considered insufficient or to cure other procedural faults in the transfer proceedings. See, e.g., Kent v. United States, 383 U.S. 541, 566 (1966); Powell v. Hocker, 453 F.2d 652, 657 (9th Cir. 1971); Kemplen v. Maryland, 428 F.2d 169, 178 (4th Cir. 1970); Haziel v. United States, 404 F.2d 1275, 1281-1282 (D.C. Cir. 1968); State v. Gibbs, 94 Idaho 908, 917 (1972); Knott v. Langlois, 102 R.I. 517, 529-530 (1967); Dillenburg v. Maxwell, 70 Wash. 2d 331, 355-356 (1966). Indeed in some of these cases the Juvenile Court has been permitted to receive additional evidence. See Kent, Kemplen, and Powell, all supra.
The lesson that may be taken from the present litigation is that, in the relatively few cases in the Juvenile Courts in which the transfer question arises, the proof should be full, and in the still fewer cases where transfer is ordered, the findings should express the judge’s reasons in fair detail and with logical cohesion.
3. The petitioner has argued that if, on the record made to the time supervisory relief was sought, it could properly be held that the case must stand trial, then that trial would have been so long delayed since the parties were ready for trial that it must be considered not “speedy” under Barker v. Wingo, 407 U.S. 514 (1972); see Commonwealth v. Look, 379 Mass. 893, 897-903 (1980). The present record on the *564matter of delay is unsatisfactory, particularly as to claims of prejudice arising from alleged increased difficulties in establishing alibi and so forth. On a superficial view, although there are surely signs of sloth on the part of the government, there is also doubt whether the petitioner was vigilant in pressing his rights. Especially in light of the course the case is now to take, we think we should decline to rule on the issue of speedy trial.
The case is remitted to the county court for the entry of an appropriate judgment in accordance with the directions in point 2 of the opinion.
So ordered.