How can I repair the scroll ball on an older Mighty Mouse?

Try flipping the mouse upside down and rolling the trackball on a piece of paper, giving it an occasional tap to help dislodge any debris. Since the trackball is depressed while rolling , this helps debris escape from inside the housing. The paper will also help absorb any oil from your fingers that have collected on the ball that may allow debris to collect inside the roller mechanisms.

• The 'official' Apple fix is to first spray the paper with alcohol cleaner, then roll the ball over it. This has always worked for me, never had to take apart.

This video tutorial entitled "How To Clean An Apple Mighty Mouse Scroll Bar" may help.

I've had this problem with multiple mice in the past before. The roll on paper did work for a few weeks months (I usually applied a few drops of alcohol to the ball before doing it). But essentially when this problem starts, the mouse is going downhill and nothing much can be done about it (the problem will reoccur within shorter and shorter time).

I tried opening two of the mice which didn't respond to other solutions anymore, figuring I couldn't damage them any further because they were already useless anyway. It worked with one with little damage to the case and putting it together with a few drops of glue. The other, while managing to open it with little damage, failed to work afterwards because I damaged the insides of the scroll ball unit.