Can someone knowledgeable please confirm or point me in the right direction.
I am not the above but will give you what I know and perhaps it will help.
You said earlier "Immediately after it ran for a period with the start button held down" does this mean that the unit runs OK if you hold the start button down?
If yes then I would look at the belt/idler switch.
I am doing some guessing here as GE likes to keep all tech data a secret and I do not have access to it. But I did find a general wiring diagram (See below link) for a GE and it shows that the start switch is wired in parallel with the belt/idler switch which will kill power to the unit's motor.
Could be the switch itself or that the belt has a problem or the idler is bouncing around too much.