Carl Hutzler's Blog

Whether you have a corded or wireless version, sometimes the trackball will get gummed up with oil/dirt. Since the mouse does not come apart very easily and the parts inside the trackball are very tiny anyway, taking it apart is not a very good option. The best approach I learned today (at the Apple store in Reston) is to simply take a piece of paper and turn the mouse upside down and roll the trackball around on the paper. The oils and some of the dirt come off on the “rough” paper. My experience using this method restored my track ball to 100%.

This may also be a good approach to cleaning blackberry trackballs. They are very similar mechanisms inside.