Jake, all you said in your post in the third paragraph is what is happening. The constant sparking, and transistor overheating happens at the same time. If I just start the engine, it's fine, but if I move the magnet to the hall and keep it there, it constantly sparks and heats the transistor on the hv board. At first, it was the dim led, then all this started. Maybe it is holding the pin low too long? Not sure since I have no real test equipment, just plug & play.

John