Q: We have a CNC lathe with GSK 928TC CNC control and stepper motors, the original motor lose its step with big vibration, now we have change a new motor, but the same problem still there, why?

A: The stepper motor could be too small, try bigger one.

GSK928TC Specification:

http://www.cncmakers.com/cnc/controllers/CNC_Controllers_for_Lathes/GSK928TC.html