64.—(1) Except as provided for otherwise in these Rules, a tribunal shall not decide any question unless all members are present and, if any member is absent, the case shall be adjourned or referred to another tribunal.
(2) If a member of a tribunal ceases to be a member of the Tribunal or is otherwise unable to act before that tribunal has commenced hearing the case, the President may allocate the hearing of that case to a differently constituted tribunal.
(3) If, after the commencement of any hearing, a member other than the Convener is absent, the case may, with the consent of the parties, be heard by the other two members and, in that event, the tribunal shall be deemed to be properly constituted.