Devcon paste two part mix , Use a dremmel to remove down to bare metal first then use plastic paint or scotchcoat after it has dried to seal it in.
Done it for Yonks and no probs.
BUT, if on the actual sealing surface or face, then it’s a bit more detailed… Ie: sandpaper or emory cloth, lapping paste, Brasso and finally toothepaste. After all that, use 33 silicon grease for sealing. If corrosion pitting is too deep for safe working ratings, order another unit in question and find out which bloody plonker left it that long!!!!
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