Hey BB, 1st disconnect plug at pto and put 12 volts to plug going into trans, should hear click. If no click check for good ground with test light. I found broken wires at pto clutch on 2 tractors. You will need to drain fluid from gear box, remove seat top trans cover, you will see the wires at pto, not a easy job but after repairing wire harness at the pto they have both been fixed. If not repairable trans will need to come apart. This came be done by removing fluid, top and rear trans covers. remove other parts as needed. Not a really hard job if you put removed parts in order.