Hi all I have a gas fireplace no issues but for aesthetics I stoned my fireplace and the outer edge of the insert. Now I'd like to turn the stone 90 degrees on the inner corners and cover up the black inside trim but it contains holes that I surmise are vents of some type. The levers are all broken so I can't tell if they are functional or not. The main question is, can I stone over the holes (see pics) safely? Damper works fine and no glass doors. Big room.