Yep, set fire to my Profile elctric Cavalier. A good buddy and I were resetting the rpm and time, test running it and it caught fire. Well, we replaced everything except the motor. Still no joy. Today I removed the motor and replaced it with an new one, same brand, size, etc. The old one, upon being disassembled, was found to have a few tiny pieces of metal inside.
The big problem is learning that these things are in fact strong magnets and placing them on a beat up work bench allows them to attract tiny metal parts one would never give second thought to. After all, a Fox will not attract metal fragments, but may give you a few.