Mine has a wooden clothes peg goes on top of the screw to provide the clutch.
Not pretty but it works and that's with WO stating it was impossible to fit an electronic unit to that particular focuser (Synta DDG).
I removed 4 screws, had studs with female threaded tubes machined up which replaced original 4 screws and provided securing points for 4 screws to hold the motor plate in place.
https://i.postimg.cc/cCqnxFfN/IMG-1028.jpg
https://i.postimg.cc/k4RSP06c/IMG-1027.jpg
There's actually clearance between the nut and the nylon roller, it just doesn't look like it and tension is adjustable via the spring.
Far from pretty but only a working concept. I'll make it look prettier one day, MAYBE............
No electronics shown in images, I have them somewhere here.
Maybe once I get the milling machine set up in the garden shed (after I weld a frame for the thing, I have the steel, welding skills and necessary equipment to MIG, TIG or arc weld the thing up) I can do something better.
One day, hopefully I'll just drop dead before one day comes, I have so much to do.........ONE DAY......