Video Problem with New Hermes 810 NHI810

Several years ago the internal monitor stopped working on our 810.
After opening the case I saw that I could easily connect an external composite monitor and I have been running it that way for the past several years.

Just recently I have lost video output.
All I am getting is sort of a rolling pulse.

I have tried another external monitor just to make sure that the problem is with the 810.

If anyone has experience with this problem or has access to a service manual I would appreciate any help I can get.