That is good to know -- I am glad I bought a new board. When I got the cabinet the A and B boards were taken out of the case and rammed together. The cabinet is incredibly clean and looks brand new. The connectors are super clean too.
My +5v is reading 5.06 volts. That is about right, right?
5.06 should be sufficient. since it's impractical for me to test 60+ power supplies for our games, I can sense when the exhibited behavior is power-related and throw my meter on it. I've had to replace both power supplies in my Daytona USA twin. periodically the game after being on for a few hours would scramble up the screens, and was even more obvious by the fact that the two linked games would be out of sync. a test on one side showed up at 5.50(!)V and the other was real low, about 5.02V (gotta remember those boardsets consist of about 5 interlocked boards -- lot of mouths to feed).
likewise, our Road Burners was right next to my SFA3 machine, and I was playing SFA3 and noticed that Road Burners just kind of said "screw you" in the attract mode and flashed a hard disk error. now I knew the power supply was suspect, because when we got that game as part of a huge game lot we purchased, I noticed the cooling fan in the power supply was locked up and dead. friend of mine works for Best Buy, he had some extra 80mm fans laying around his house, so I swapped a new one in. would you believe that game worked for about 11 months with a +5 set at 4.82V ??? the hard drive ran off the board power connector! you can tell the power supply is shot when if you adjust the +5 pot and you can't get it beyond 5.05V. this one, luckily, adjusted out nice. it's just got mileage on it. gotta figure these video games we got are 10-15 years old, lot of them with original equipment still.
stranger things have happened, though. I have Randy Fromm's Blue Book of Really Good Technical Stuff or whatever the hell the title is, and read a story about a WWF WrestleMania game where the +5 was set UNDER 5.00V and the game worked fine. when the power supply was bumped up to what I think Fromm typically uses (5.10V) the game started resetting and exhibiting all kinds of strange behaviors. so there's some game hardware out there that can function perfectly fine even when the +5 is set too low, and there's obviously hardware out there that demands a little bit more.
I'd try bumping your +5 up to 5.15V, see if there's any change. there probably won't be. if you're uncomfortable making this adjustment, then don't mess with it, it probably won't make a difference anyway. case in point, my Daytona that was pushing 5.50V ? yeah, broken +5 adjustment pot. the power supply bottomed out to 0.03V, after which I immediately cut the power. older PSU's can be fickle like that, but I understand they're not exactly the cheapest item to replace, Daytona demands one of the beefier 200W Happ units, but it's a very important component all at the same time.
shitty power supplies can be the difference between your game working ok and your game DYING.
sorry for the long post. thought I'd throw some more anecdotes from my year of doing this tech shit at you. I guess it's worth noting that I learned how to do it from my vast computer knowledge and spending my entire life playing games in our past arcades (we had a grocery store with like this video game cellar dwelling, and even had the cockpit versions of Sinistar and Star Wars in it!)