Did you check to see if the 12V supply to the camera is working? Red inset LED next to the 12V jack on the camera should be lit. You need that supply even if the camera is not being cooled.
Also, it looks like the two captures that you posted are slightly different, although both are still saturated. Remove your camera from the OTA, place the original M42 cap on it (or a M54 cap if you have swapped to the M54 tilt plate) to seal off all light, and see if it looks more normal (basically a dark field of just noise). (And don't forget the 12V supply.)
The fact that the defect shows up as strips that are parallel to the scan lines is not very promising, though.
Chen
