, in any event where an arbitrator has to be replaced during the course of the arbitral proceedings, a substitute arbitrator shall be appointed or chosen pursuant to the procedure provided for in that was appli- cable to the appointment or choice of the arbitrator being replaced. This procedure shall apply even if during the process of appointing the arbitrator to be replaced, a party had failed to exercise its right to appoint or to participate in the appointment.
2. If, at the request of a party, the appointing authority determines that, in view of the exceptional circumstances of the case, it would be justified for a party to be deprived of its right to appoint a s ubstitute arbitrator, the appointing authority may, after giving an opportunity to the parties and the remaining arbitrators to express their views: (a) appoint the substitute arbi- trator; or (b) after the closure of the hearings, authorize the other arbitrators to proceed with the arbitration and make any decision or award.