Problem With Z axis

Hi all,
The Z axis on my M1000 keeps dropping out. It will be all working well cutting out a job and all of a sudden the Z axis will lose power and plunge into the job. The Z axis then becomes unresponsive and the only way to move it is by manually rotating its lead screw by hand. It seems to be a problem with the circuit board. If the Z axis circuit board is swapped with the X axis board the problem will move to the X axis and the Z axis will work. the only solution so far has been the replace the circuit board.

The machine is only a year old and this has happened multiple times. The time between failure is not consistent, some last for months other weeks.

Any help would be appreciated.