Hi everyone. I recently got an old Williams Tri-Zone from 1979. It's a System 6 machine.

I am in the process of getting this machine up and running after some quite severe batteri acid damage. And I have now turned my attention to the display part.

The problem is that 3 out of 5 displays only show the upper half. The bottom half is dark. I have attached a video to show it.

Does anyone have an idea what could be wrong? I personally don't think it it the displays, but suspect the MPU or driver board.
Any hints where to start, or how to debug this?

Thank you so much in advance

Video:

Thanks, i will definitely check that out. Although I don't think any of the mentioned issues in PinWiki matches what i am experiencing. So i am still hoping someone havr seen it before, or would be able to conclude something based on the video