Sounds funny but try steeping it in coke overnight. If no luck that way try a little gentle heat over the gas ring but watch You do'nt overheat it. Billy
gentlemen, as much as i hate coke, the legend on corrosion is a bunch of crap many parrots, but who actually tried it ? i did - worthless on metal & copper the stomach on the other hand is another matter
i prefer the light heat to loosen that part meself mate