I am delighted with the outcome, but it was a very hard-won battle.
A few things I learned:
- Persistence. Never give up.
- Each camera truly is different. I've now used several d800s, and each of them focuses just a little different. I never took AF fine tune seriously. Now I understand why there is a +/- 20 adjustment range. Even good cameras focus differently given the same lenses.
-- No need for elaborate testing. Is it in focus or not? This is different from documentation of a problem. Evidence trail is important. A lot of time has been wasted with elaborate focus-test setups. Think about it: There is never a request for proof via rigorous testing that a camera is focusing correctly.
-- There are people at Nikon who care about customers and communicate with them -- and who can make decisions to help solve a problem. These are not generally the people who answer the telephone. They may care or communicate well, but they have zero control over any outcome other than bidding you a pleasant day.
-- These forums are invaluable. I never would have noticed the left-sensor problem had I not learned about it online. I understand that is ironic. However, had I NOT learned about it here while everybody else knew, I would have a resale problem way too late to do anything about it. And when I did use the left sensor and it was fuzzy, I would have chalked it up to the usual cull shots I am susceptible to.
I am so very happy to have a working camera. Now the limiting factor is completely behind the viewfinder.