I picked up this old Gillette this morning. The Pat. date of Nov 15 '04 is stamped on the outside of the handle, but the serial # on the screw-in handle bottom dates it to 1905. It appears to be silver-plated aluminum. It is almost completely black with tarnish. What would be the safest way to clean this up without risking plate loss? It's in fairly good condition and I don't want to ruin it.