My guess is that you have this mount https://damencnc.com/en/tools/kress/...ling-motor/147 and there is a plate bolted to the mount, which in turn bolts to the Z axis and it is the plate bolted to the mount which has worked loose.

If that is so you will need to dismantle and reassemble using threadlock. There is also the possibility that the bolts are slightly too long and are bottoming on the thread. Anyway, you will need to get it apart to see what is going on.

Yep, the red wedges are too thick, try a green one

Rob