Lawnmower Shorted out

I have a corded B+D Lawnmower model MM1800. It had jammed up with clippings and stopped turning. Maybe I was slow to release the switch handle because it tripped the circuit breaker. I reset the breaker but now it doesn't work. The motor spins freely and brushes look OK but when I pull the switch handle the breaker trips again. Is there some type of fuse in the lawnmower or did I somehow fry something in the lawnmower wiring, I have it apart and I don't see any fried wiring. Could it possibly be the switch in the handle? If so can I purchase a replacement?