Use a chrome cleaner, like Solvol autosol.

You will only be buying time I'm afraid, and will need a re-chrome sooner or later as the seals will only cope with a certain amount of damage.

My FJ ones are bad, and I've got them through the summer, but I think it's rechrome time now...
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MC21SP Plaything
BMW F800GS Bumblebee
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