Stabilant is a really interesting electrical contact enhancer. It is very expensive, but only a tiny amount is used at a time. It can be had via auto parts channels as Standard Motor Products #SL5 or NAPA Echlin #CE1, and it's also widely available through electronics supply houses. A potentially lower-cost source is here. I paid C$35 for a 15ml bottle of 22a with three applicator brushes.
You may read about it here and here (automotive-related application notes from the manufacturer; there are field notes for other applications easily navigable from either link).
More interesting, less sales-oriented field notes here, here, here, and here (this last link is a long page, search on it for the word stabilant).
I was a skeptic until I tried it.