Here is the wiring diagram
http://www.servicematters.com/docs/wiring/wiring_main.htm

I am assuming when you say it stops the motor stops.

As you can see there are not many parts in the motor's cicuit.

1. First try it while pushing the door closed. Could be the door switch is just making and the vibration opens the switch.

2. Try holding the push to start switch closed if it runs as long as the switch is pushed ( a couple minutes or so) then the motor's centrifucgal switch is not making properly.

3. Try a different time setting coulld be the timer is shot. Niote this does not totally rule out the timer.

4. Did have one fellow with this symptom and it ended up being a loose connection in his electrical box. Check the breaker connnections and the connections at the plug. Also would check the connections at the terminal strip in the machine.

Could also be the motor is overheating. If this is rthe case you will not be able to restart it right away. The motor's thermal overload cutout waits till the motor cools down before it will reset. Also it will stop faster the next cycle as the motor is already warm.