This is a common problem with that model and I have the same problem. The problem is that the headphone jack is not secure to the board. I have mine taken apart on the table and am looking for the solder points to resolder them. I am not sure how tech savy you are as far as fixing things and soldering. But I can almost promise that is the culprit.
Scott
January 2010
Sounds like your poor player has had a hard life! It may be time for a new one.