Logitech MouseMan User Manual page 11

Maintaining the Mouse
If the cursor skips or moves abnormally, you may need to clean the ball of your mouse.
1. Remove the retainer ring to remove the ball. On the bottom of the mouse,
press in the direction of the Open arrow imprinted on the retainer-ring cover.
2. Wipe the ball with a clean, lint-free cloth,
then blow carefully into the ball-cage
to dislodge dust and lint.
Inside
roller
3. Look for a build-up of dirt on the rubber
roller(s) inside the ball-cage. This build-up
usually appears as a stripe running around the
middle of the roller.
Ball cage
4. If dirty, clean the roller(s) using a cotton
swab moistened lightly with isopropyl (rubbing) alcohol. After cleaning,
make sure the roller(s) are still centered in their channels.
5. Make sure that fluff from the swab is not left on the roller(s).
6. Replace the ball and retainer ring.