Not sure why you have 2 threads for the same issue but as I stated in your last post:
On the TC's the seat switch and the parking brake switch will not stop the engine from turning over but they will cause the fuel solenoid to shut off... so check both of those first.
The fuel solenoid is on the right side of the tractor on the same side as the ignition switch and down by the oil filter. If you set the parking brake and turn on the key, you should be able to hear it click.
If the fuel solenoid is not working & the engine cranks but will not start, it is most likely related to the seat switch or broken wire in the seat switch circuit or a bad fuel solenoid. It also could be the operator safety module, but I would check that last last after the seat switch wiring or bypass is verified good.