Silicone grease (in the tiny gray tubs sold
by HD) works well for this.
For general contact cleaning
, you can buy contact cleaner at HD or at Radio
Shack. Originally sold
as "tuner cleaner" for the old TV channel changers. It fixes electrical contact pretty decently. We cleaned up a balky head pump
this weekend. Also works for radio
knobs, and car window switches, among other things. I think I've used it 2 or 3 times as often on other boats, as ours. Almost always fixes the problem. Then at THIN coat of silicone grease to protect.