If using brass anti-backlash nuts, instead of the delrin ones, the holes for the 8mm M3 screws are too loose & not tapped. I solved this by using 10mm M3 buttonhead screws and corresponding M3 nuts, and installing them in the opposite orientation (nuts on the outside of the couplers).
This is a tricky fiddly thing to do without catching the springs on the anti-backlash nuts in an unsatisfying way
Front Z lift assembly PDF - sheet 8 of 22
If using brass anti-backlash nuts, instead of the delrin ones, the holes for the 8mm M3 screws are too loose & not tapped. I solved this by using 10mm M3 buttonhead screws and corresponding M3 nuts, and installing them in the opposite orientation (nuts on the outside of the couplers). This is a tricky fiddly thing to do without catching the springs on the anti-backlash nuts in an unsatisfying way