Re: Rubber bands
Last century I spent a while dealing with end-users and their faults. We tried to avoid sending an engineer half way across London for simple calls, such as "erratic mouse" reports.
Most of the mice were Microsoft ones, which were quite decent quality. The rollers were actually metal rather than the cheapo plastic ones.
Speak to the user and introduce them to the extraction of the ball of their mouse. "You see the two metal rollers?" "Yes." "You see the two little rubber wheels in the middle of them?" "Yes." "That isn't rubber. It's gunge."
Shortly thereafter, they could wander round their office earning themselves brownie points for sorting out everyone else's erratic mice, thus keeping our profits up.