I sent my 24-700mm to Melvile for a zoom repair in September. It just came back last week...two weeks later than expected due to hurricane Sandy...and to my surprise, it was significantly back focusing on my two D800e bodies. I ran my FoCal AF fine tuning with one body and the tuning went from zero done in August to -18. On the other body, I could not adjust AF fine tuning enough to make it work.
When I called Nikon, they requested JPEG images shot with both bodies. So now I have to wait for Nikon to mull over my images before a decision is made re doing the repair again. This could go on forever. Glad I have a 50mm f/1.8 as a backup lens!