I can understand J7's concerns. If I strip the arm down myself and damage something then I can spend the time to hunt down replacement parts, find someone to fabricate them or decide to accept the loss. For J7 he would be taking money to work on someone else's arm, he could not afford the time to hunt down replacements and trashing an arm would be bad for his reputation. If he has plenty of work, why take on the risk?
I did notice an omission my original post, forgetting to mention that I had the Zeta serviced and re-wired with VdH wire by Moth in 1997 (I believe they hired the engineer from GB Tools who used to build Zetas etc). I am not sure whether they would have applied fresh oil/grease at that point (or left it without), certainly 20+ years in California will have a drying effect. As an alternative cause, could there be tension in the wiring? I had a cartridge fitted 5 yrs ago and the dealer insisted on adding colored heat shrink to the cartridge tags (but got the colors wrong!). In looking closely it seems that there is more wire exposed at the head shell end than there used to be, so it could be tight going through the bearing.
btw I realized I had mentally upgraded my cartridge when I made the first post - I have a Lyra Kleos, not a Skala. Unfortunately, being a "New Angle" design, sound quality drops off very rapidly if it is outside of a very narrow 0.1g window.