I have a wired Mighty Mouse where the ball stopped working, and all attempts to fix it were unsuccessful. I liked the suggestion of using Goo Gone, but I mistakenly used Goof Off Pro Strength Remover instead. I poured a little into the hole and started rolling the ball around, and the Goof Off immediately started dissolving the plastic, and white sludge started coming out around the ball. I quickly dunked the entire mouse in a bowl of rubbing alcohol to rinse out the Goof Off, and then drained the alcohol out and let the mouse dry. I thought for sure that I’d ruined the mouse, but once it dried out, it now works perfectly again. So, I’m not sure I’d call that a recommendation, but if you have a mouse you’ve given up on and are going to throw out anyway, Goof Off might be a last-chance thing worth trying.