[COLOR="DarkRed"]Start with disassembling and washing in warm soap/water (providing there are no paper tags on it). Just dish detergent, mild stuff like a biodegradable detergent.
Then you wanna try some metal cleaners. NO BRASSO, NO NOXON...it's too caustic for this, probably.
I suggest Hagertys 100...it is a silver polish and it is very non-abrasive. Pic a spot on the shell which is not very visible, and try a dab, see if it helps. If not, stronger stuff may be req'd.
[/COLOR]
[COLOR="Purple"]the badge looks almost "Duplex"-ish[/COLOR]