Repair 60/40 center armrest?

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I have the 60/40 split bench with the center armrest, and the PO must have used it as a seat or something, because the bracket on the passenger side is loose from the seat frame. I know it has bolts that attach the armrest to the hinges, but the hinge itself seems to have separated.

Is that hinge welded to the seat down there?

How could I go about repairing it?

Thanks for your ideas!