I received a new D600 from B&H in New York this January. About June I noticed a lubricant spot on the sensor. I sent the camera body with two photographs showing the spot to to the Nikon Repair center located at 6420 Wilshire Blvd, Los Angeles CA. I was only expecting them to clean the sensor and I was completely unprepared for their response which was:
Replaced Shutter Mechanism
Adjusted Auto Focus Operation
Checked Bayonet Mount
Checked Image Test
Cleaned Image Sensor
General Check and Clean
I feel completely overwhelmed with the detail Nikon responded with here. They must have re-engineered a new shutter mechanism to prevent future spotting, my old one was working fine. I know that you have been critical of them at times, but they certainly deserve some Atta boys here. I just had to pass this along to you. (jm)