OK thanks, I'll monitor it more closely and see what happens.
I might borrow the shop "Chassis Ears" & clip the pickups to the stepper motors and run some code. It's a 4-channel amplified audio rig with headphones we use to pinpoint wierd mechanical noises in cars we work on and should make it easy to hear any funny stuff going on.
I could also rig a DTI to the axes and run some repeating codes to see if it returns to the same spot each time. Don't wanna wear out the teeny little leadscrews & nuts though. They have a very finite lifespan:
