We had 2 Hero2's I took down on a trip. 2 nights before I put the everything together the camera, dive housing, lcd's and backplate and realizing the light and motion camera action tray needed the tripod base. Needless to say it was a mess of boxes, manuals and I broke the plastic locline base that L&M made. I did manage to engineer a better one, but a few seconds before the "CRACK", my wife says "don't break it!" great....
Anyway fast forward a few days into our trip and I keep seeing this mark in my videos so I decide to take the 2nd Hero2. Unbeknownst to me I had the LCD backplate with the ventilation holes...........ooops. DOA And I did manage to get rid of the dirt that was causing the mark on the first Hero2. Wife was NOT happy.
The reason I had 2 setups was for one for my wife and one for my son. I ended up doing 99% of the filming, it took quite a bit of work in the water to get it set with the filter and lanyard. So after I got the routine down I was the designated cameraman.