If you ever open one up and pull the armature, resist the urge to, or otherwise avoid, sticking it to steel surface, such as your laser's cabinet. I did that tonight, by accident, didn't think much of it until I put it back together and found I have a totally useless stepper motor now. No torque, nearly all the resistance is gone.

I'm guessing the act of it sticking to my laser's cabinet de-magnetized it. Not fully, but all it does now is skip around and squeal at anything faster that 30% speed. And there's no way to slow down the initial high-speed acceleration at every change, so it's pretty much useless...