Grinding on the Z axis

i have been running the printer for about 2 years no issues all of a sudden the grinding started.
i ordered a new stepper motor. installed but same problems… if i switch the cord from the 1 stepper motor to the other one it seems to make the noise on the other stepper motor.
extreme grinding
any ideas??
Thank you.

What do you mean by “seems to”?
Without diagnosing the actual problem we can narrow it down to electronic if “seems to” becomes “definitely”.
On the main board, there is a ‘driver’ for every stepper, so if everything else works…start by replacing the stepper driver.

Depends on the board. Some stepper drivers can be replaced and others can’t (easily). That becomes a MB replacement job.