My bad, but I hope someone can help
I purchased a 500A at a thrift store last week. I was soaking dirty parts in evapo-rust and now the bobbin case and 4 screws look like they have a silver tarnish. I think I know what I did wrong. I soaked a latch that may be aluminum or some other metal in with the things that now appear tarnished. I know it was my bad, but if anyone has any suggestions for getting rid of the tarnish, I would be grateful. Thanks!