I just received a used 6D I bought from a fellow POTN member. When I mounted a lens on it this morning I found that there is an apparent problem with the camera.
In comparing the action of mounting a lens on the 6D versus mounting the same lenses to my older T2i the 6D seems to be a much tighter fit (more effort involved in spinning the lens) and a louder(maybe raspy?) sound as the lens is turned to lock in place. Mounting the same lenses on my T2i results in a much smoother and quieter installation.
When installing a lens on the 6D it is easy to turn until the red dot approaches the small screw on that side of the camera. When it reaches that point it begins to tighten up significantly and requires more force to turn.
I tried installing all three EF lenses that I have on the 6D and all three lenses appear to do the same thing. These three lenses work fine on my T2i. After trying all three lenses I discovered that there is a burnished/rubbed-looking area in the vicinity of the camera's mounting ring that is close to the screw. There also appears to be "debris" (for lack of a better work) that is being left on the camera's mounting ring in that area. The debris (metal plating?) is easily wiped off so I'm not sure whether it's coming from my lenses or the camera's mounting ring. I've included a couple of images of the area that appears to be the problem.
Anybody want to venture as to what the problem is? This was a really major purchase for me and I'm thinking something is wrong here. The seller is stating that he had no problem with the camera. This is about to make me sick.
[IMAGE'S LINK: https://flic.kr/p/pQjkr4]IMG_6505a (Custom) by Intheswamp, on Flickr