Hey buddy...

Usually that indicates a bad contact. Did you buy it new? sound like it may be a few years old. If it hasn't been damaged by a fall or ? , then it could just be that you blew a cap. Be it contact or cap, a repair could cost over $100. Unless you are good at that sort of thing. First try spraying some contact cleaner up under and toward the back of the key. You may have to remove the case to do this. As you said, it is a key that is seldom used, so it may not be worth the aggrevation.

toucher