That's one of the things I would look at. Basically look at all the "safety" no-start switches and their wires. My seat has two of those switches, the PTO one, the clutch has one, the hand brake has one, and I'm sure that there are more. Every one of them has an adjustment. Last time mine wouldn't start it was one of the seat switches....actually it was the wire to a seat safety switch which had migrated over to the seat spring so that when I sat down in the seat the the safety switch actuated properly and the engine started, but then later on when I shiftted positions the current through that switch was shorted to ground by the seat spring - which blew the fuse.
So the symptoms were that the tractor would be working fine when for no particular reason the motor would stop. And then the starter wouldn't re-start it. Investigation showed all the safety switches were fine, but a fuse was blown. I'd replace the fuse and all would be fine for awhile until the motor stopped again. Another fuse. Again and again.... until I just happened to notice that seat switch wire...
rScotty