Why have you got nuts behind the stator plate?
Hi Robin
Not sure what you mean by a stator plate? in the 2nd picture the left hand and middle plate are clamping the original nut, tightened by the middle nuts (to resist rotation). the delrin nut is fixed to the right hand plate and is adjusted by the end nuts to compress both drive nuts to reduce backlash.

The spring is purley overkill and just pushes the delrin nut on to the adjuster nuts and also ensures that if I back of the adjuster nuts then the delrin nut moves with them to give positive control over the pre-tension.

Ive tried 3 or 4 different versions and this set up worked the best, is the easiest to align and easiest to adjust.

I presumed that there is always a fine line between eliminating backlash and excessive friction?