OK, I put this in the Apple-1 area because many people use vintage chips in the Apple-1 replicas and the Mostek RAM chips, among others, tend to tarnish or have corrosion.
So I have tried the TarnX solution which is an acid which is used to clean silverware. It can make the legs brittle by micro-pitting them.
I was using an art eraser but you need to put pressure on the legs, which means you need to be very very careful.
The best thing is an abrasive block that Speedy got me from Germany which destroys itself while you are using it, but doesn't require much pressure. I lost the packaging so I'm not sure of the brand.
What do you guys use? I'm actually hoping someone has found something that works as well as the block Speedy sent me but that I can buy it myself in the states or on Amazon.