The magistrate may correct an illegal sentence at any time and may correct a sentence imposed in an illegal manner within the time provided herein for the reduction of sentence. The magistrate may reduce a sentence within ten days after the sentence is imposed or within ten days after the receipt by the magistrate of a mandate issued upon affirmance of the judgment or dismissal of the appeal, or within ten days after entry of any order or judgment of the appellate court denying review of, or having the effect of upholding, a judgment of conviction. The court may also reduce a sentence upon revocation of probation as provided by law.