Are you thinking about selling your D600 and try from a new lot?

I had issues with my D2x years ago and eventually gave up trying to replace it with multiple bodies and accepted second best. At that point I went down the route of cheap bodies and spent more money on the lenses.

Although the experience was not a total waste of money it did sour my attitude to Nikon.

The fact that there is no public recognition of the problem I think makes it worse.