I fought with those connectors, tried burnishing the terminals, even replaced them with another unused connector, pin-by-pin. The real problem was in the female side, on the backplane of the machine. So, I individually removed those terminals (PITA) and replaced them with new ones from a smaller connector. It fixed the problem, so now the BEAU connections are all intact and working properly.
I think the better fix would be to remove those connectors completely, and replace them with the pigtail version of the Molex pin connectors, similar to the normal Bally reels of that era. There's a lot of connections back there including the segment driver pins for the LED display on the door - that one was a problem as well, where some of the segments wouldn't light, and wiggling that connector would make them blink.
Do you have the Summit Service Manual?