A first swap drives, see how. If the swap is a swap drive the phenomenon of drive problems, not drive without problems.
2 to the drive circuit board have any questions, may x - direction of the line is disconnected.
3 motherboard with no problem, the external optocoupler board is often bad, x-direction of the signal may simply never sent to.
4 buttons with no problem, left itself may be bad.
5 have no problem stepping motor, stepper motor may be bad.
Careful observation of mechanical parts 6 have any questions, you may be stuck framework.