If by reason of death, sickness, or other disability a judge before whom an action has been tried is unable to perform judicial duties after a verdict is returned or findings of fact and conclusions of law are filed, any other judge regularly sitting in or assigned to the court in which the action was tried may perform those duties; but if such other judge is satisfied that the duties cannot be performed because that judge did not preside at the trial or for any other reason, that judge may exercise discretion to grant a new trial.