The acme screw has been very hard to turn ,
I slightly elongated the two mounting plate holes that line up
With the Delrin nut allowing it to angle slightly where it wants to them tighten
The screws ,
It works so much smoother now
got the same problem, on upper z position, the axis is jamming
i just unscrew a bit the the two screws that connecton the spindle mount and Delrin Nut
and i have no more problems
(the screws can’t unscrew more due to the spindle that block them…)