Yesterday i got a 1925 peacedollar and it is AU-50 with some tarnish should i remove the tarnish or leave it?
I would say leave it alone, unless you really know what you are doing. If you don't you could ruin a nice AU coin.
maybe just put in acetone for a minute. some of that may be dirt and the coin will lighten up a bit, or not. but getting dirt off is good,