|Dennis M 1064
Upload & Sell: Off
It looks like a chunk (albeit a tiny chunk) of foam. Like they use for dust seals or light seals or what ever it is. I had it in my old EOS 10S, and it never went away. I was more agressive about trying to get it out on that camera. No sensor to worry about. It was above the focusing screen. My Sony TRV103 Video camera developed a similar issue, and there is nothing to even open! So, this was certainly an auspicious beginning with my 5DIII.
So, I just did it all again. Lens off, tilt body down, blow out with Blower. I then look into an LED flashlight and inspect for dust. This makes the forth or fifth attempt over a one week period. This time. . .it worked.
SPECIAL NOTE**** The secret is, you have to post it online, whine and cry, blubber and bawl, then it will let the crap go. This way, you seem silly.
I recommend this particular method before sending your camera back to Canon.
To quote Roseanne Roseannadanna, ". . .never mind".