Like many people, I had an Apple Mighty Mouse that stopped scrolling downwards. Actually, I had two problem mice: one at home, the other at work. Initially, the cleaning technique of rolling the ball upside down after gingerly dabbing some isopropyl alcohol onto it offered temporary relief, but eventually nothing could dislodge the buildup.

Finally, the mouse at work stopped scrolling altogether. Based on the results of a Google search, the only option left was, apparently, to tear it apart so that I could clean it out by hand. (A former colleague came up with the absurd suggestion of threading a thin strip of adhesive tape around the ball to pick up the gunk, an idea which I dismissed out of hand as both impractical and unwieldy.) I didn’t feel like going to all that trouble to work around Apple’s design flaw resurrect a mouse, and I didn’t have any superglue on hand to put the scrollball collar back together.

Out of frustration I finally ended up going for the Hail Mary play and trying a suggestion I found: immersing the mouse, upside down, in a container of 70% isopropyl alcohol. It’s important to keep the mouse upside down for two reasons: first, the gunked-up ball assembly’s immersion is ensured; second, the third-button functionality is provided by a small switch that dissolved gunk will settle down into if the mouse is right-side-up in the alchohol, rendering the ball-click utterly dead. If you want to keep your third Mighty Mouse button alive, keep it upside down during the chemical cleaning process.

After a few hours in the alcohol I drained the mouse, placed it upside-down on a piece of paper, and rolled the hell out of the ball. Like some kind of nasty ball-point pen, it left a trail of squashed gray chunks of goo and alcohol across the paper. I kept rolling until I couldn’t coax any more liquid out of the thing and let it dry, upside-down, for a couple of days. Good as new! Your results may vary, of course, but it’s worked for me on two separate mice.