Duty of Fact Finder. Except when an agreed statement of facts is submitted by the parties, it shall be the duty of the fact finder to hear and consider evidence submitted by the parties and to thereafter make written findings of fact and a proposed disposition of the grievance which shall be advisory in nature. The proposed disposition shall be based solely on the interpretation of the applicable provisions of the M.O.U. and other personnel rules if applicable to the grievance, and he/she shall not add to, subtract from, modify or disregard any of the terms or provisions of the M.O.U. or such rules.