(a)During trial. If by reason of death, sickness or other disability the judge before whom a jury trial has commenced is unable to proceed with the trial, any other judge regularly sitting in or assigned to the court, upon certifying familiarity with the record of the trial, may proceed with and finish the trial.(b)After verdict or finding of guilt. If by reason of absence, death, sickness or other disability the judge before whom the defendant has been tried is unable to perform the duties to be performed by the court after a verdict or finding of guilt, any other judge regularly sitting in or assigned to the court may perform those duties; but if that judge is satisfied that a judge who did not preside at the trial cannot perform those duties or that it is appropriate for any other reason, that judge may grant a new trial.