Lots of photos:
Untitled by
Scott, on Flickr
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Scott, on Flickr
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Scott, on Flickr
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Scott, on Flickr
Untitled by
Scott, on Flickr
Untitled by
Scott, on Flickr
So I found a driver that fit. All the screws (actually steel) were tight. Loosened, adjusted the ring, tightened. Still slipped. Did that a bunch of times. No joy. Loosened the screws further, and the focus ring popped off. Interesting. Lots of old, congealed grease on the underside of the ring. Cleaned it off. Will need to put some PTFE grease on lightly at some point. Pulled one screw all the way out. Also turned the helical manually toward a minimum focus. Turned, but actually pretty stiff. Not an Agfa, but not smooth, or easy.
So I've got two thoughts: 1. The helical is stiff enough that this weird little locking system that joins the focus ring to the helicoid can't deal with the shear and slips. 2. The screws might should actually clamp down from above, and what little bit of head on the screws should hold the ring tightly down, which is not how it was attached. I'm leaning toward #1. I can't rotate the helical any further at this point; not sure it's at minimum or not, but don't want to force it, or unscrew it to where the two helicoids separate (been there, done that, have the tee shirt). So, I think next step is a tooth brush with some xylene on it to clean the threads as best I can, lightly grease with my decades old PTFE grease (maybe mixed with a modicum of Rem oil), work it around manually, and see if that's golden. Elsenhow, punt.