Thanks for all the help, Looked at the tractor today and it has three wires for the solenoid, Black, White, Red with black tracer.
Testing the three showed it is getting the correct voltage,
Black is ground.
White 12v when cranking.
Red 12v when key released.
I ordered a solenoid today that should be in next week so I'll put it on Friday and see if we are back running.
Thanks again.
Just a small point, but one wire should be powered all the time, except when the key is turned to the off position. The other wire should only be powered when the key is turned to the start position. White would be the start wire, and red would be the run wire according to your voltage measurements.
IF you red wire is not energized when the engine is cranking, then during the transition in the key position back to the run position, the the solenoid could move to the stop position before the run coil was energized to hold the armature in place in the run position.
In other words, IF the red wire is not energized ALL the time (except when the key is in the off position) you likely have an issue with the key switch.
My GUESS is your key switch is probably OK, and you may not have measured the red wire voltage when the engine was cranking.
edit: You do not need the engine to be cranking to make the voltage measurements. You can do it with the solenoid unplugged at the connector.
