The kill switch is a simple switch. The fact that one breaker point set shorts without affecting the other indicates it is picking up a ground some ware. Running OK when the switch is not pressed indicates the Magneto is OK. I would suspect an internal fault in the stop switch. If it is a new switch, it may be the wrong one. Disconnect both magneto wires at the switch and see if touching them together kills the engine. The switch for the magneto ignition is different from one for battery ignition. They are easy to mix up. . .
Good Luck ! ! ! 😀
