Liquid cleaners work. I used to have a bottle of stuff that was supposed to be applied with a Q-tip. I don't know if any liquid like that is still around.

I think someone mentioned awhile back that there is an anti-corrosion fluid available from electronics supply houses.

It's ironic that this topic popped up just now. Not long ago I found a bag of servos I've had stashed away ever since the RC frequencies changed and we had to upgrade all our TXs. I dumped the obsolete TXs and stuff in a garbage bag and quit the hobby. I couldn't see paying to get that many transmitters upgraded. Sold my planes and bought a couple of target rifles. (and then Clinton was elected..... jeez, can't get a break anywhere )

When I found that bag, first thing I did was look at all the connectors. Looked like new. Think the pins were all gold plated. No corrosion problem for sure.