Welcome to the forum. Here's an Owner's Manual for that tractor. It has a wiring diagram and parts list in it also. There is a relay hooked in with the PTO wiring. If you can unhook the connector at the PTO clutch and jumper (+) & (-) to that, you should be able to hear the PTO work (engine OFF). Sometimes, it's just a matter of corroded connections, possibly at the switch, relay, or the PTO itself.