This is getting weird. Yesterday I caught sight of hyper tuning an EQ5, I have an EQ5 and wasn't sure what could be done. It was on the Darkstar site who belt drive EQ6's etc. No belt drive for an EQ5 seems not possible.
Right to maybe relevant bits.
The Dec worm drive is held by 2 O rings APPARENTLY. Now O-rings to me mean rubber, but dimensions seem odd for rubber O-rings. I suppose there is a chance that this has changed since the initial question was asked think I read 2010, basiclly the O rings are poor and die.
Darkstar do a tune which is basically all the change assorted EQ5 bearings and fit alternative somethings. Including to the Dec worm.
Reading the Dec worm is the one to look at. The tuning to the other items is replacing one bearing with another, maybe better one but nothing significantly different.
The Dec is a problem, putting new O rings in is pointless, so they fit a bearing (?).
However further reading the worm bearing hole is 11.3mm dia, the worm shaft is 6mm. There is no corresponding bearing with that outer diameter.
Someone on Iceinspace took an 11mm/6mm bearing wrapped insulating tape and pushed it all back in. They said it did a good job. Maybe better then a worn perished O ring.
Darkstar mention a ceramic bearing (?). But I do not know if this implies they take the worm bracket and over bore it to 12mm, or if the ceramic bearing is like a bronze bush, and produced to 11.3mm.
After about 4 or 5 sites I decided that should I ever need or want to do anything I would likely get a small piece of bronze bush/bearing material at 12mm and have it turned down to 11.3mm and have a 6mm central hole bored. Then put the new assembly back in. And so have bronze bushs as the bearing material.
Not sure if Darkstar would modify just the Dec worm, as that way you take the bracket out, with worm. Wrap it up, box it and send them. But there is no mention of such - could be worth asking, as it would be a much nicer and simpler upgrade. Even if not a full tune.