Soft scrub should work, but you might also try "Bar Keepers Friend." It's a powder and very Comet/Ajax-esk (nice word, huh) and will be near them in the store (usually a Gold can with a Blue white lettered logo). Unlike Comet/Ajax it is virtually non-abrasive. I always have a can in my car-wash bucket of stuff. I use it on car windshields to metal bumpers on Classic vehicles. It's original use was as a metal polish to remove rust.
Works great for me.