There is a decorative (non-structural) beam that runs the length of our living room ceiling. The room has a 12ft cathedral ceiling. The beam is supported by two carriage bolts driven through the beam in the middle of the room and into the attic. A steel cable is connected to the top of the bolt, attached to a turnbuckle and then secured to a rafter. Only one of the bolts has a turnbuckle and the cable on the other bolt is simply wrapped around a nail in a rafter and is no longer taught. A previous owner installed two ceiling fans dramatically increasing the load on the beam. Over time the beam has begun to slip creating a gap up to half an inch. What is the best way to secure the beam and reduce the gap?