Btw i bought small steel wire wheels at china freight to put in my drill to buff and polish up all this stuff after chemically cleaning it, and neutralizing it. CLR or tarnex works great on tarnish too.
So does ketchup! Yep, that's right, ketchup, catsup however they want to spell it, lol. That's what I used to clean the contact surfaces and my gauge cluster.
Just rub some on, let it dry up a little and wipe it off with a damp rag.