This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
It does sound like you have a gunked-up mouse. Rollers are whitish plastic, black plastic, or metal-- they do not have treads. The "tread" is gunk. It is best to clean a mouse with the computer OFF. The main reason is that, otherwise, it's hard to avoid unintended clicking on stuff that could cause problems. There is no need to disconnect the mouse unless you want to move to a better work area for the cleaning. First, get together a few supplies and tools: A wooden desoldering stylus or flat-tipped plastic TV technician's tool is handy for dislodging gunk. (Probably, a small jeweler's screwdriver is okay. However, you do not want to scratch a roller.) Small skinny long-nosed pliers are good for picking out globs of gunk and dust. Windex or some relatively safe spray cleaner. Paper towels and a cotton swab. To open the mouse use fingernails to rotate the panel insert around the ball opening on the bottom. The panel and ball should come out. Spritz the ball and panel with cleaner (or put them in a glass with soap and water). Wipe dry. Dampen a paper towel with cleaner and wipe the outside case. With a cleaner-dampened paper towel, clean the cord for at least a foot or so near the mouse. Look inside the mouse. You may see globs of dust and gunk. Remove these- - pick them out-- as best you can. Inside, there should be 3-4 rollers. If it's been a month or more since the last cleaning each will probably look like it has a dark gray rubber tread. Use the desoldering stylus, etc. or a fingernail to dislodge gunk on each roller. The best way to dislodge gunk is to push the 'tread' sidewise (kind of like removing a tire) as you work your way around the roller. Use the skinny long- nosed pliers to pick out strips of the 'tread' as it unpeels. Use a cleaner-dampened swab to finish cleaning each roller. Use the swap to wipe around and pick out any remaining dust or gunk, replace the mouse ball, and rotate the plastic panel into place. One way to simplify mouse cleaning is regular timely use of an Ergotron "Mouse Cleaner 360" or similar kit. The Ergotron kit includes a couple velcro balls, cleaner, wipe cloth or shammy, and a mouse cleaner track pad. You squirt cleaner on the proper size ball, stick it in your mouse, run it around in a circular motion on the track pad, and finish up with a wipe using the cloth or shammy. Such kits do not seem to be much help in removing established gunk 'treads'. (Actually, the Ergotron might get the job done; but, it would take a lot of revolutions. It is easier to dislodge 'treads' by hand and use the Ergotron to get rid of residue.) Cleaning kits can avoid tread build-up if used every week or so. By: Rubywand ----------------------------