I'm not sure that Wilcox-Crittenden who originally made that stuff is still in business, but Marinium is pretty easy to restore with a buffing wheel. It's relatively soft and will polish up nicely. The Marinium deck pipe in this picture is over 30 years old, but after a few minutes on the buffing wheel, it looks like new!
I sprayed it with a clearcoat coating from Eastwood called Nyalic to keep it looking that way.
BTW, if you need one, I still have my old marinium bow light I removed when I installed the anchor bracket.