Thank you for your question.
I am sorry you are having a problem with the tractor. If the engine will not turn off when you turn the key off, I recommend checking the kill wire from the ignition coil first. Regardless of any of the interlocks, the engine should die when the switch is turned of. To check the kill wire, trace the black wire from the engine to the ignition switch. If you do not find a break in the wire, you will need to remove the blower housing on the top of the engine. Once it is removed, you will be able to trace the wire from the ignition coil to where it connects to the tractor harness. If you do not find a break in the wire, run a wire from the black on the tractor. Once you start the tractor touch the other end of the added wire to the frame. This should kill the engine. If the engine dies, use an ohmmeter to ohm between G and A1 on the ignition switch. If it shows open, the switch is defective.
You can order the parts for the tractor from the following link.
Craftsman tractor parts
Once we have the engine working with the ignition switch we can diagnose the interlock problem if it is still present.
I hope this is helpful. Please let me know if you need further assistance.
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