My point was that the coil may not be getting battery voltage with the key in the start position, but is in the run position. Need to get the volt meter out and check for power to the coil in both the start and run key positions.
We have to be very careful how we say this. If a coil gets battery voltage, it is blown in shot in under a second!
What happens is the kill switch tab on the coil is grounded to the machine when the key is in the opposition but of course not when it's in the start or run position or at least that's the way it's supposed to be.
We don't want anyone to ever shoot 12 volts to a coil because it will likely damage it and quickly.
Flaky switches do this all the time. This problem is likely a messed up switch if no one has messed with the wiring.
EDIT: I just found what kind of engine we're talking about and it has a automotive style coil with a plus and minus apparently so that's why I was confused.
I was thinking traditional lawn mowers and not old school tractors. lol
Maybe that's why the old guys always called them magneto's.