Parts come from F&P directly I think.
But I fixed mine by gluing a picture hanging hook over the broken plastic prong. The hook was bent to fit over it and the extra length it gave the broken plastic prong was just right to cause the sensor to sense when the door closed. The hook happens to fit perfectly in the sensor hole. It has run that way for years now.
It must be a common problem as we had already replaced the front door (the only way to properly repair it) a time before that for the same problem. Second time round I wasn't going to pay for a new door.
Allan, February 2010