Hi
Thought that this might be useful info for IIS members wishing to embark on hypertuning their EQ6 mounts and require different thicknesses of spacers for the worm ring-gear, these are made of teflon and pretty rugged - they are on special at the moment going for USD25/set (from usual price of USD40) and available from here:
http://www.astro-rubylith.com
HTH
Cheers
Bill