I had both of my cameras fail on me.... fuzzy on right and blank on left. after proving the cables ok, I bit the bullet and ordered replacements. $250 each...ouch!
After disassembly of the camera electronics I found massive corrosion on the CCD board and the power supply board. Probably caused by previous owner power washing the coach... (they ruined the headlight lenses that way too)
Also exact replacement is not possible. the new camera is smaller so I had to make a cover plate, paint it to match and install the cameras after painting them also.