So, to follow up, I have a question. When you say "I have removed the teak decks" : did you do that yourself or possibly you supervised it. Is the original plywood sub deck still there? If so, can water be seeping down into it? I am certain that my staining is coming from that area (which one cannot see) and I don't see any evidence of it coming from the bronze.
I am attaching a photo of how it appears on my boat.
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