Just bought myself a new DS Lite 2nd hand. Found that the R button is getting jammed by something. It likes to lock up and requires a lot of force to get it to move. Once pressed it will work okay, but once I leave it alone for a few seconds it locks again. Seems like something is getting stuck in the button mechanism, but as I've never taken one apart before I don't know what it could be. Any advice? I bought a tri-wing screwdriver in preparation for removing the back cover, and getting to the buttons seems easy, so I'm pretty sure I'll be able to fix it whatever it is.