All of a sudden my nail gun is not functioning. When I push the tip up against the tip, nothing occurs, the motor doesn't start. I've taken the head off, put the battery in and pressed the micro-switch which results in the motor starting. Lift the micro-switch up, the motor runs on for a while. Repeated this Several times before reassembling the gun only to find it's as before, not working. It's as though the bit that slides and makes contact with the switch isn't reaching it. Nothing is bent or misaligned, any thoughts? Thanks in advance.