By letter filed with the Clerk of Council, the Manager shall designate a Municipal department head or other qualified Municipal employee to exercise the powers and perform the duties of Manager during the temporary absence or disability of the Manager. If such designation has not been made, and the Manager is, in the opinion of the majority vote of the Council, unable to perform the Manager's duties or to make such designation, the Council shall, by motion, appoint a Municipal department head or other qualified Municipal employee to perform the duties of the Manager until the Manager shall return or the Manager's disability ceases. During such absence or disability, the Council may revoke such designation at any time and appoint another Municipal department head or other qualified Municipal employee to serve until the Manager shall return or the Manager's disability shall have ceased. After thirty (30) days absence or disability of the Manager, the Council may declare the position vacant.