I have a set of Phidget Bipolar stepper motor drivers (1063) running 4 NEMA-17 bipolar stepper motors (42BYGHM810) in a sample handing system (controlled via python). Everything has been running well but suddenly one of the motors has started to randomly move in a back and forth fashion. Often it will run fine, but occasionally when the program tells it to go one way, it goes the other. Sometimes it jerks back and forth in a continuous fashion after being given the direction to move to a new position. I've double/triple checked the wiring.
Have anyone seen this behavior before? Do you suspect its the motor or the controller or both? Any ideas on what can be done to fix it/troubleshoot it? Or what I should replace first?