I have a PC monitor that works fine except for an intermittent that I have
traced to the connection between the pins in the neck of the tube and the
small pc board that is mounted on them.

Although I can't see the socket surfaces, the pins appear to be the problem,
with a dark coating that does not respond to the mild cleaners I have tried
so far. I am assuming that if I can clean the pins properly the problem will
disappear, however some form of surface treatment that leaves a non-reactive
conductive coating would be a better long term solution.

What options exist for treating the pins to leave them with a non-tarnishing
finish that will help ensure a reliable contact with the socket?