I think your display is outgassing. This is how they go when they have burned themselves up. On screens with a lot of dots lit, some of them don't light.

Might be low voltage; a higher voltage would help the display be useful for a little longer. I don't have the schematic for that board, but you should check the test points against the schematic.

The batteries are a red herring, but if you're getting a message about that, it might make sense to look for corrosion on your MPU board before it gets worse. Does it reset the scores when this happens? In any case, this is *not* causing your display problem.

I would be a suspicious of the power supply. I know it's new, but I have heard tales of aftermarket power supplies, particularly Rottendog, not being quite right in some games. Unfortunately, I'm not sure where you'd get a stock power supply, or that it would fix your problem. If you had another DE game of similar vintage, I'd swap them to see what happens. Ultimately, the question is whether or not the power supply (and basically nothing else) is putting out enough oomph to make the display work. Usually this is a low-voltage condition or the display is bad. Since the display is known good (and even if it's "new", test it in another game to be sure) that leaves the power supply.

You might also check the voltages on the display. I guess it's possible that there's an excessive voltage loss in the harness.

I might investigate an LED display. These should be a lot less picky about power supply.

Thanks for following up! This is helpful to know.