[Amps] How to restore oxidized tank switch

[LB3HC]

I have digged thru my junkbox and found an old tank switch that I
bought at a swap meet. The switch have ceramic deck "holders" and
looks like it is quite rugged. You can see some photos here:
http://picasaweb.google.com/106642167576607300202/LinearAmpParts?feat=directlink
I consider using it on my new GS35B design. However I need to restore
it as it is badly oxidized. I tried to use some kind of metal on some
other equipment one time and that removed the silver coating(!). I
don't want to damage the silver coating on this nice switch. Please
share your techniques and tricks for restoring silver plated / silver
coated parts.

73
LB3HC