Cleaning Trackball Balls
Trackball balls pick up dirt and oils from your thumb (you dirty person) and have to be cleaned. Before you moan about how optical mice never need cleaning, think about how often you clean, or at least brush something off, your mouse pad or whatever you use as such. You can keep a trackball clean in the time it takes for a large webpage to load.
For both of the trackballs we discussed above, the procedure is similar. The bottom of the trackball has a small hole (blue square in picture at right). Use your little finger, or a pen (if your little finger isn’t so little), to push the ball out. Make sure it doesn’t go flying and roll off when it pops out (see next section). Don’t let it get scratched; give it a wipe with a clean, dry, lint free cloth. I find a microfiber cloth for cleaning glasses is best, but a handful of t-shirt you’re wearing will do in a pinch.
Put the ball where it won’t roll off and your pets won’t get a hold of it, and take a look inside the cavity it came from. There are 4 places where dirt will gather. Three small bearings (yellow square, pic at left) that hold the ball while allowing it to spin, and the window for the optical sensor (in red). Use a Q-tip (or finger) to wipe gunk away from the three bearings. Use a Q-tip or cloth to give the window a wipe. Be very careful with the MS Trackball, since the window has a hole in it. If something gets in there, it can sit right in front of the sensor. You can solve that problem if you have a tiny screwdriver and a lot of patience. Best to avoid it altogether.
Give the cavity a last wipe and blow in it to get rid of anything you knocked loose but didn’t remove, put the ball back in, and you are done. You can moisten your cloth or cotton swab a very tiny bit with warm water, and, in the case of the bearings (not the window or ball) alcohol. Personally I have never had to go further than a dry cotton swab.