Unidirectional rodent needs a MightyCleanup
Since a few days my MightyMouse's scroll ball didn't scroll down anymore, only up. Small objects can be big annoyances sometimes.
Spraying some kitchen cleaning solution on top of it, and vigorously rubbing the wheel on my pants brought it back to life. And might have cleaned the pants as well.
They say you should only use water, but it worked for me. YMMV, of course, and it might not work will all pants either ;-)
Thanks Benoît for the hint!