"That is, 20/3.5 Nikkor UD, 28mm/3.5 Nikkor H, 35/2 Nikkor O. No slop, just enough drag to give a good feel. "

That's the thing, mine don't have enough drag to feel like the focus is under control. You'd think since they are the old lenses with fluted focus ring lenses that they'd be too stiff from dried grease but these are not that way.

Probably cost more then they're worth to have some one thicken up the grease.