Hi All, Received sensor cleaned D600 from Nikon about 4 weeks back (Shutter mechanism replaced, Sensor cleaned) . After 700-800 shots oil blobs appear again, also Camera Hot Shoe malfunctions with external flash ( after Nikon servicing my camera). Called up Nikon USA, sent them sample they advised to send camera back along with my speedlight. I am sure they will take another 4-5 weeks to clean/fix it again. Question : Has any one experienced same spot reappearance issue after Nikon Service ( Had read one thread where Nikon Australia giving an option of refund or buying D800 with difference of price) . Please advise what should I do ? I have lost faith in the system. Thinking of writing to Costco to return my entire set back (not sure after 8 month after buying it they will honor this return.) I have used many Nikon cameras for last 26 years, starting from FM/FM2/FE/FE2/FG/N65/80,D50 now D600 I was never so disappointed. Any advise from experts will help.