The original OpenSCAD source file is a bit of a mess, so I am hesitant to share it without some cleanup and documentation. Please bear with me.
That said, I shared the original design with the hope and intent that people would use it, and where possible, improve it. So my Thingiverse files are there for anyone to use, freely.
@SusisStrolch I am glad you were able to modify the STL files to remove the ridge. Please feel free to share the remixed file on Thingiverse if you are so inclined.
I would also be very interested to hear about your experience using the Drylin bushings. I haven’t used these before, but would expect these to have more friction than the steel bearings. How do they perform compared to the stock brass bushings?