For the purpose of these Rules, a casual vacancy in the office of a member of the committee occurs if the member:

1. dies; or
2. ceases to be a member of the association, or
3. becomes an insolvent under administration within the meaning of the Corporations Law; or
4. resigns office by notice in writing given to the secretary; or
5. is removed from office under Rule 20; or
6. becomes mentally incapacitated; or
7. is absent without the consent of the committee from all meetings of the committee held during a period of 6 months.