I tired several methods which worked to some extent
(afore mentioned silicone tubes, shrink wrap, eBay bought molded rubber overwraps,
machined grooves and add O-rings), but now I just strip my capstans clean and coat them
with plasti-dip. Methods in shown my various videos (like here
https://youtu.be/cTZCD4OXETk ). Only plastidip and o-rings have been durable enough in the
long run, and plasti-dip is easier. I have not done a capstan this large though. There are
also some folks out there that will also commercially recoat a capstan with correctly
molded and vulcanized rubber.
Marc