- Nikon has acknowledged, found and understood the root cause of the issue. It has been eliminated in the current production (however, I guess we'll never know when and from which serial numbers on).
- The root cause is a misalignment of the AF module when mounted, outside of Nikon's own production tolerances. But be asserted we are still talking micro meters here ...
- The issue for affected D800 can be solved in selected Nikon service centers; such as Düsseldorf, Germany.
- The procedure is currently rolled out to more Nikon service centers.
- The fixing procedure for Nikon is a tedious one. It includes writing individual calibration values into the firmware. For larger deviations, the AF module will first mechanically be re-aligned. This may actually include the AF auxiliary mirror in some cases.
- This method is believed to deliver an autofocus precision which is at least as good as of cameras from a fresh batch. I could not clarify if there is a chance for both methods being non-equivalent in some way. However, Nikon Germany does not think so. They rather wholeheartedly believe that the in-service calibration procedure resolves the issue as good as current production does, if not better.
- Nikon does actually not know how many D800 of the early batches have been affected. Despite all oddities, the so-called service-rate of the D800 is unremarkable and only "sligthly increased" (compared to other camera models).
If you have contacted Nikon support for this issue, please share your experiences in the comments section below (mention also your country).