(a) When the mandate of an arbitrator terminates, a substitute arbitrator shall be appointed according to the rules that were applicable to the appointment of the arbitrator being replaced.
(b) Except as agreed by the parties:
(1) if the sole or presiding arbitrator is replaced, a hearing previously held shall be repeated; and
(2) if an arbitrator other than the sole or presiding arbitrator is replaced, a hearing previously held may be repeated at the discretion of the arbitration tribunal.

(c) Except as agreed by the parties, an order or ruling of the arbitration tribunal made before the replacement of an arbitrator under this section is not invalid because there has been a change in the composition of the tribunal.