My fireplace can not be used as smoke is coming into the house at the vents above the fireplace doors. Fire place was inspected by a certified fireplace chimney service and t was determined that the metal on top of the fire box at the seam from left to right has openings. Can this be repaired in order for the fireplace to be safe and functional. We are in the process of selling the home and this became evident during the Buyers home inspection last week. Please advise of my options. Thanks in advance"