I don't remember those having black headers. had one at a location completely scorch the top header, the pins were purple. lol
I had no 90 degree replacements on hand either, so I had to improvise and seriously stole one of the unused headers off the opposite side of the board.
I can't remember if we changed the power supply out afterward or not. that's pretty nuts if a little screw terminal unit could do what it did.
that said, I don't think power is your issue. 80% of all games in free play arcades are sitting at about where yours was set at, about 5.6V, and those games somehow survive 14 hours a day, every day. I'm still thinking you have a ribbon cable or interconnect issue someplace.