My Yellow Drum Machine (perhaps I sould find another name? .. Anyways, it is using small motors instead of servos.
So motors are constantly fired to hit a drumstick - end then the motor returns to it´s original position via a spring mounted on it.
All the sudden nothing worked, and so I thought I had bunrt something, as the motors constantly send current back when the spring returns them. .(And we are talking thousands of stick-movements)