If at any time after a trial or hearing has been commenced, but before the final order or judgment has been issued, the judge is unable to proceed, a successor judge shall be assigned. The successor judge may proceed upon certifying familiarity with the record and determining that the proceedings may be completed without prejudice to the parties. In a hearing or a trial without a jury, the successor judge shall, at the request of a party, recall any witness whose testimony is material and disputed and who is available to testify without undue burden. A successor judge may also provide for the recall of any witnesses.