Heres a few things to check:
- Are you able to pull back on the white compression collars of each lead nut to compress the spring? If not, that is the issue and those need to be pulled back.
- Loosen the mounting screws for each lead nut but don’t remove them. Loosen them to the point that the lead screw can float, but still transmit torque. Jog each axes and see if there is any binding.
If step 2 is successful, the check to see if the lead nuts are resting flat against their mounting surfaces. If they do, then jog each carriage until they are adjacent to the lead screw bearing couplers. Then tighten the lead nuts. Be very careful not to deflect the lead screw when tightening. Consider tightening one screw and then jogging to make sure that it still jogs without binding. Then tighten another and do the same, etc.
If one or both lead nuts are not making good contact with their mounting flanges, let me know and I will give you a call.