Sounds like you may have ground loop issues. The reason it looks ok with your hand held mon. is because it's isolated from power ground. To eliminate this problem go to the camera and isolate it from any metal. I would bet your mounts are attached to metal that is grounded or you have intentionally grounded your cameras. You can easily test this by temporaraly taking your camera off the mount and placing it on a piece of cardboard to keep it from touching the mount. It dosen't take much AC on the video ground to distort the picture. If you ever see the distortion move slowly up the screen you can be sure you are seeing 60hertz hum. The reason it slowly moves up the screen is because the scan rate of a color camera is 59.94 hz, the ac power is 60 hz so they are almost in sync but not quite, hence the slowly moving bars. Of course if your camera is line locked the distortion will be stationary since the scan rate of the camera is now locked to the 60hz line frequency. Good luck!