These games are over 20-30 years old - we have to accept that things are going to fail.
Capacitors are starting to go all over those boards now. If I bought a non-reissue DMD bally/williams game now I would be changing a load of electrolytics and all those ribbon cables.
Indeed... Electrolytic Caps have a working life of approx 20 years, so these will all start to fail soon ifnot already... Is a similar scenario to all the Monitor Chassis needing a rebuild... (But i know you know this!)