I have a DIY cnc router running GRBL 1.1 on an Arduino UNO R3. Been working fine for several years but yesterday I noticed that the Y axis (a 570 in/oz stepper) running a 3-1 T5 on T5 belt drive) was missing steps and acting jerkey. BAAAD PARTS. Grrr What could it be. I don't detect and impingement with the bearings. The belt does not appear to be slipping or skipping. I can actually see the stepper jerk. Bad stepper? Bad driver?? I don't have a spare motor but I could buy one.
Any help would be appreciated,
Thanks