Hey Mitch,
between ball screw and stepper there is a coupler.
Did you have a look at the “Support” Playlist at OnefinityCNC’s youtube channel?
There you find e.g.
-
Support : Replacing The Ball Screw on the Onefinity CNC
This video shows what’s in there. - Tightening the coupler on the ball screw // Updated for quick access holes // Support
- Tightening a loose wiper in the foot of the Onefinity CNC // Support
- How to clean the ball nut on the Onefinity CNC // Support
Did you also check point 7.) of Troubleshooting: Rail is getting hung, stuck, or out of alignment ?
Also I remember there was this mysterious issue some time ago. When an axis blocks, the stall detect function of the TI stepper driver chips is triggered which leads to the Onefinity controller thinking the axis has done stall homing and resetting the axis position value to 0.