Comment by magicalhippo

Is it possible to rest the switch on the notch? Does the switch make contact if the switch is in the RUN position but the switch is not completely down?

That is, is it possible they flipped the switches over to RUN but did not seat the switches properly, and instead leaving them on top of the notch, with later vibration causing the switches to disengage?

Just trying to think of some semi-plausible non-active causes.