Maybe these manuals can help.
Japanese manual:
https://archive.org/details/cz-605-d-cz-613-d-instruction-manual/page/2/mode/1up?view=theater
English manual:
https://archive.org/details/cz-605-d-cz-613-d-instruction-manual/page/2/mode/1up?view=theater
Oh ok. HAS video output goes to Analog RGB port. X68k computer video goes to the same port. I remembered I had to toggle between digital and analog between computer (digital) and game console (analog). But game console I connected to composite video audio inputs on the monitor.
Probably try adjusting pots or knobs I underlined red on pictures (I used Google Translate to translate). The image correction you adjusted is for computer (when you connected to Sharp x68000 computer or other computers). The image correction I underlined on picture is for tv.
色の濃さ : color...
Looks like the pcb cracks on traces. You can try to bring it to PNL inc to take a look at it. Or call John and send him these pictures if they can fix it.