Your best bet is to ask the question on a tractor forum.
First thing I would do, check that the battery has at least 13.2 volts while running. If the alternator is not charging the battery, the clutch will quit. The battery has to has at least 12.3 volts resting.
Next you have to see if said voltage is getting to the clutch by testing at the wire terminal.
Next check to see if voltage is getting to the clutch switch.
You could also have an issue with the safety switches. Many times, the seat switch is the culprit, but not always.