Pronounced pity!

As a professional photographer who photographed for about 20 years with Nikon (KB), I realize that the D600 is an excellent camera in the FX segment.
I would also point out that "my" camera (Ser 603XXXX) is affected by the debris problem.
Below is an excerpt of the repair process at NSP DüDorf who is very friendly and customer-oriented went from equip the rest:

Goodwill (SR)

Service Packages

Intensive cleaning of the mirror box, the oscillating mirror mechanics and the sensor area. Preventive measures to reduce dust entry and turbulence have been made. Please note that SLR systems are not fully closed and can be done through the use of the future entry of dust (eg when changing lenses / focusing or zooming operation, etc.). Please follow the instructions in the user manual - pages 301-305.
As a preventive measure carried out the exchange of the closing unit.
Update Firmware.

Spare Parts

1F999-708 - SHUTTER PLATE UNIT
1K935-331 - DOUBLE STICK TAPE B
1K935-332 - DOUBLE STICK TAPE C
1K935-334 - DOUBLE STICK TAPE F
1K935-335 - DOUBLE STICK TAPE G
1K935-336 - DOUBLE STICK TAPE H
1K935-337 - DOUBLE STICK TAPE I

While the sensor is cleaner than before, but already in the first photo are again this typical spots (ol increased) surfaced.
For me, a camera is a key tool with which I earn my livelihood. Poor tools are simply a nuisance.
It suggests itself to me the impression as if Nikon has still not found a probate repair method.

In sum, calculated as the review of my experience with the D600 only one star.