Could be a sign of outgassing...at least with the “R” photo...

Second photo is puzzling...I can’t tell if the secondary letters are just a reflection of itself or if that’s actually within the display segments.

Yeah, I had a very similar thing happen to mine a few days ago...others thought it was the outgassing issue which is what happens to those plasma Displays over time...things start to break down and the gas could pass into other segments. At least that’s how I understand it.

This is not out gassing, this a UND chip on the display driver board that is going bad. This chip is leaking voltage partially lighting the segment. These chips are no longer available, so the board can only be repaired with a used chip. The other issue is that these early WPC games with alpha numeric displays are not very common. But there is a led display replacement when you want to replace it.

But the segment that’s partially lit shouldn’t be lit at all...

UND chips convert 5 volt signals from the CPU to 100 volt signal to the display glass. If there is some leakage of the 100 volt side of the chip, there will be partially lit segments were there shouldn't be.

Ah, that makes sense!

Might be a UDN chip going bad, but I have also seen this happen because of the black dust - basically soot/carbon - accumulating on the high voltage carrying foils and parts on display board. The dust is conductive and causes leaks. So clean the display glass connector and boards, use smooth brush or compressed air.