Grinding noise and drift on x-motor mount:X (1 reply)

Hi.

I'm exploding this forum with my messages at the moment. All help is appreciated.

I'm getting some drift in one of my axes. I followed a lot of guides that I found on the web about:
tension of the timing belt
calibration of the stepper drivers
mechanical alignment
etc.

Originally it was my x-axis that was grinding and drifting, so I thought it might be a mechanical problem. I decided to change the x- and y-motors on the sanguinololu connection. That is, I left the motors in place but switched the connection, when the board tries to drive the x-motor it drives the y-motor instead and vice versa. Result: The y-axis is grinding instead.

Then I thought it might be the stepper driver that is faulty. So I switched the x- and y- stepper drivers, put back the x-motor on the x-connector and the y-motor on the y-connector. Result: x-axis grincing and missing steps.
So I try the fourth and last combination, switching the x- and y-motor connections. Result: y-axis grincing and missing steps

For a summary:

Case/motor/stepper driver/motor mount/result
1/x/x/x/bad
1/y/y/y/ok
2/x/x/y/ok
2/y/y/x/bad
3/x/y/x/bad
3/y/x/y/ok
4/x/y/y/ok
4/y/x/x/bad

So, what this tells me is that:
Both x- and y-motors are ok
Both x- and y- stepper drivers are ok
Motor mount x is not working properly

Now my question is, where can this come from? I have the DRV8825 stepper drivers and I have put all jumpers on the microstepping switches under the drivers. Can the microstepping jumpers be the problem?
I am using Sprinter firmware, can this be the problem? What should I try instead in that case?

Or is it simply my board that is screwed?

Thanks for your help.