How to fix a Mighty Mouse trackball

For anyone still using Apple’s Mighty Mouse:

When your trackball no longer scrolls, dab it lightly with a disposable lens-cloth. Then turn the mouse upside-down and roll the trackball on a clean index card. Roll in every direction. Be vigorous. Be very vigorous.

I have tried other fixes for the trackball problem without success. The lens-cloth fix — which I just made up and tried out — works. It really works. I was mildly astonished by the amount of gunk set free.

Details: I used a Zeiss “pre-moistened” lens-cloth. It’s available from Amazon and other sources.