As I was mowing the mower stopped suddenly and I saw the black plastic piece come out of the discharge chute. It was very hot so I knew it was part of the mower. The mower cranks but will not fire. I opened the engine compartment and found a magnet broken and stuck to the side of the engine compartment. It appears that this magnet fits in the black plastic piece. I've looked and cannot figure out where it came from. Any thoughts? Thanks.