Drill the plug out with a holesaw and a template to drill out the remaining parts of the plug and resin. Might need to pull it out with plyers. Fill hole 1/2 way with resin and cab-o-sil. Slide your fin tab into the new plug (do not screw) and drop it into the hole while sliding other tab into existing 2nd plug for alignment. Push the plug down until the tabs touch the glass. The jig will act as a resin dam, fill in the rest of the hole with resin being careful not to overfill and get the screw submerged in resin. When cured remove fin and template, screw down the screw, and sand the plug and resin flush with the board. For additional strength you can laminate a patch of 4 oz. fiberglass over the plug, hotcoat and sand. Good as new.