Can a judge change or modify a sentence or discharge a prisoner after Rule 35 of the Criminal Code has expired?

If the court vacates and sets aside the judgment of conviction, then, of course, the prisoner must be discharged, or granted a new trial. If the sentence, as distinguished from the conviction, is illegal, then it may be corrected. But a judge cannot, without vacating the conviction because of a legal defect found therein, change or modify, after Rule 35's sixty day period has expired, a sentence that is itself proper, legal and lawful as a sentence. Richards v. United States, 94 U.S.App. D.C. 85, 212 F.2d 453, 454 (1954), cert. denied 358 U.S. 886, 79 S.Ct. 126, 3 L.Ed. 2d 114; Affronti v. United States, 145 F.2d 3 (8th Cir. 1944).²