Quoted from JoeNewberry:
I think those may be latches for the 100,000 point lights. One for each player's light. Probably the safest way to keep those lights on without cooking a coil.
Ahh, I never thought of that! D'oh! Thanks!
That's probably it. It's my first game with those lights (besides 1,000 point digit light-ups, but that's like 10 years older), that explains it.
I guess I got the good end of things, talk about two relays that are the least likely to be used out of any other on any machine... player 3 and 4 100,000 lights, quite the long chain of requirements needed to utilize those, funny. Still going to fix it soon of course, cool to know I can likely proceed without them (with them disconnected) though for the time being just for testing purposes. I assume they're probably universal with other Williams games?
Quick EDIT: I think the Player 4 one might have faired okay as well, just fell off the board. I'll have to look. Player 3 is completely obliterated and missing pieces. Could probably just make my own too with ease if I don't find matching ones, but matching would be nice.