problem may be in the slide bearings. can u post photos of the slide Bering, then we can say adjustable or not.if not adjustable you should relapse the bearings.
Before i had same problem of our CNC milling machine. the holes was not smooth and vibration when cutting. the reason was loosen the check nut of the X axis ball screw.
so check the machine completely and tight if any loosen components
- some bearings can adjest, send photos
-not difficult, but u have to mark all component (or get photos) before de-assemble.
- relapse ball screw support bearings also