Looks like I am in a similar boat as the OP, as Nikon has my D800 for the 3rd time right now only they claim they can't find anything wrong with it. Unfortunately, it seems that they are unable or unwilling to read my letter explaining what the fault is. (In my case, after the first--successful!--AF repair, I could no longer MF based on how sharp the image is on the focusing screen. (I did careful testing after consistently missing MF.) Second repair botched the AF again without helping MF.)

When I get the camera back in hand, I will try your procedure as well. Thanks for the suggestion.

I have a D800E that can AF and MF, so I know how good life can be....