Thank you for choosing Nikon for your photographic needs.
Some D600 users have reported the appearance of random spots on their images which is generally attributed to the natural accumulation of dust.
While understanding that dust will occur over time, and steps may be taken to reduce the occurrence, the complete elimination of these dust spots may sometimes be difficult.
It has come to our attention that, in some rare cases, they may be reflected noticeably in images and removal may be difficult using normal measures. Therefore, Nikon is informing users of a service to reduce this issue. Resolution
As a first step, please follow the guidance from the D600 User's Manual (pages 301-305) related to the Clean Image Sensor function and manual cleaning using a blower bulb.
If these measures do not remove all dust particles and you are still experiencing problems, then please consult your nearest Nikon service center. The technicians will examine the camera thoroughly, and service it as needed. Requesting service
See the following for instructions on requesting service by a Nikon service center. http://www.nikonusa.com/en/Service-And-Support/Service-And-Repair.page
Please direct inquiries regarding this matter to your nearest Nikon service center.
We hope that you will continue to choose Nikon for your photographic needs.