Quoted from SteveCooling:reseated all the cables to the display board, no change. They all look ok
Reseating does nothing to fix bad cables, except to introduce one more lost cycle in the life of the plug.
Replacement and repinning connectors is the only reliable fix. You can meter them out for continuity, but even that won't guarantee identifying the current handling capability of a poor connection.
Quoted from SteveCooling:Other future-proofing tips specific for these machines? (Batteries are corroded, at least needs a change - looks like no board damage from a brief inspection)
https://pinside.com/pinball/forum/topic/williams-system-11-bullet-proofing-thread