I have a problem w/ my ti keyboard, the mod wheel quit working on me.

At first, a few months back, it would work for a while when I first start her up, but then would quit on me by about ten minutes into a session. So, I am not too savvy w/ electronic repair, but if it is an easy fix, or if someone knows the mechanics of the ti mod wheel, perhaps I can look at it myself.
Are there any pictures of an open virus? Anyone have experience with this type of thing? Any help is appreciated.
Regards,
Michael