Pink or grey horizontal lines on video dow...

recently I was trying to download video to my computer. In doing this the recorded tapes showed (and downloaded) the video with wide horizontal pink or grey digital lines across the images. When I tried to play it back on the camera it does the same thing. I tried cleaning the head but it hasn't helped. I also tried the fast forwarding recommendation for someone who had blue lines in camera. When I made the tapes they were fine. Now we are also getting a blank screen when we are in record mode.
I have 4 of these cameras. I teach middle school video technology, so they do get a workout, but 2 of my cameras have thick pink or gray lines on playback. One of them has even quit that and just has a blue screen when in record mode. Please help.