TL;DR - I don't know what provides the "motivation" or friction for automatic tonearm start, and what to adjust or grease to fix it.
It's Garrard servicing week for me, it seems. I decided to tackle cleaning up the Zero 100 which has given me a new-found respect for how strong Garrard cement is. It took me several minutes of direct heat from the mini torch along with levering (more than I liked) and prying to free the Stop Lever from its post.
I've cleaned everything off and reassembled it dry for test fitting. All the linkages are free, the cam spins nicely; the Delrin parts of the cam are free. I'm a bit in the dark, however, because I don't have an example of how things should be assembled when it comes to the tonearm Friction Lever and Pickup Lever; these items were stuck and twisted when I got the turntable.
It turns out the tonearm was bound because someone had either forced it or rotated the Pickup Lever on the Pickup Spindle. I put everything back together in what appeared to be the "natural" position of the parts, in addition to consulting photos of similar "big chassis" Garrard models from this site and the parts diagram.
Manually running a start cycle by hand the mechanism moves the same as any videos I've watched. Nothing binds, the tonearm is lifted, but never swings over the platter. Crucially, it appears the start cycle is completed properly, as the Manual switch stays latched in "On". Auto-return works fine because the two faces I've circled in the second photo below seem to work as expected (Friction and Pickup Levers).
- Autoslims have the Friction Link, Duals have the Steuerpimpel and Main Lever…what is performing the equivalent job in this mechanism? I don't understand what's meant to be grabbing the tonearm, and I haven't found a "theory of operation" section in any of the service manuals.
- Does everything look to be in its correct position in these photos? Am I missing any springs or connecting rods? According to the parts diagram everything's here. Dare I fiddle with the black plastic adjusting nut on the Friction Lever?
- What does the Retracting Lever I've circled in the third photo below do? I can't say that I've seen it move or really do anything thus far. Maybe once the tonearm does its thing?