That damage is the result of arcing caused by more current than the connector is designed for. Non OEM bulbs with a lower resistance would be the most likely cause.
At this point both sides of the connector are irreparable. Considering that and the fact that this connector isn't one that is generally disconnected and connected I wouldn't hesitate to cut the wire going to the bad pin and soldier it directly onto the trace on the housing. Problem solved, permanently.
William.