Hi Stan. Thanks for your comments! I have read on other websites the possibility that the dust might be caused by mechanical issues. I don’t have any direct evidence that this is the case – much in the same way I suppose you don’t have specific evidence that the dust is from a poorly controlled environment during the camera assembly. I’m not saying you are wrong – but I don’t rule out the more serious possibility. So it might be the windshield or it could be the transmission… the question is how much do I want to gamble (I’m not very risk tolerant).
I don’t own a D600. I’ve been trying to decide between the D600 or the D800. Or I might save $$ for another 6 months and get the D4. The only capability I would like to improve upon is the ability to take better indoor sport shots in poorly lit high school gyms (basketball, volley ball, etc). I currently use a D7000. Back in the day, I set up flashes in the bleachers and used my D70 synced at 1/500s to get great shots. I sorely miss the fast sync capabilities - but I don't miss having to set up flashes and worrying about some high school kid running off with one. Cheers!