(2) If or to the extent that there is no such agreement, the following subsections shall apply.
(3) Section 13 (appointment of arbitrators) shall apply in relation to the filling of the vacancy as in relation to an original appointment.
(4) The arbitral tribunal (when reconstituted) shall determine whether and if so to what extent the previous proceedings should stand.
(5) The reconstitution of the arbitral tribunal shall not affect any right of a party to challenge the previous proceedings on any ground which had arisen before the arbitrator ceased to hold office.
(6) The ceasing to hold office by the arbitrator shall not affect any appointment by him (alone or jointly) of another arbitrator, in particular any appointment of a presiding arbitrator.