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Get the heads wet and then cover them in Barkeeper's Friend powder - create a white muddy mix coating all over them. It has Oxalic Acid and will remove the tarnish. Let them sit and stew for a while and then scrub real hard with a Scotchbrite green pad. Rinse them and dry them. They will be as bright as they are going to be.
Or, send them to this guy in Georgia. His job is as good as PING factory and it's $4/head cheaper. They will come back like new.
http://www.ebay.com/itm/PROFESSIONAL-PING-IRON-RESTORATION-SERVICE-Wedge-Eye-2-ISI-Zing-/281066893564?hash=item4170e470fc:g:QnwAAOxyLN9SijJd