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.