I have a couple classic blocky Amiga mice from the A1000/A500 era. Both of them have issues tracking the ball properly. I've cleaned the ball, but the ball remains smooth/slick. It doesn't have the rubbery grip that it used to have.
Does anyone have suggestions for cleaning the ball or treating it with something to restore the grippiness? It would be really nice to move my cursor vertically at some point. 
Yeah, don't really clean the ball. The rollers, as lurch said, are the bit that need cleaning. They will be covered in gunk.
