Nice job on the mod and the write-up.
I know this is an older thread but I just got here and hope you can answer a question for me.
In your photo named Cross Feed ScrewAssy B.jpg, you show a cylindrical piece with a hex socket flat head screw (sitting in place) and two grooves for o-rings. Let's call that the nut because I assume it's threaded to mate with the end of the leadscrew.
As best I can figure the design, the nut retains the hand wheel and sets the clearance/preload on the thrust bearing. If so, then apparently, the two o-rings provide some friction to maintain the nut adjustment. Also, the end of the leadscrew is not tapped to accept the hex socket screw. The hex socket screw is fixed to the nut. Did I figure it out correctly? If not, please advise.