D600 issues resolved in new cameras?
I believe only Nikon can really answer.
That said, I understood that they very recently found a fix to repair affected cameras (all produced?)
IMHO - new cameras currently in assemby lines should be free of issue but are the ones on the shelfs of the different distributors fixed/free of issue ? Likely not.
PS - I bought mine a few weeks back in Switzerland at MediaMarkt, and they told me it was from new batches. I thought maybe I would be OK with new batches, but I am also affected with that. So my guess is that mine was still produced a few months back....
Also I am preparing to send it back since it seems the SWISS repair center seems responsive and knowing well the issue.