The barn doors in my TWD Pro won't stay open as they should. It was working fine until this morning. In the diagnostic menu for coils #4 tests the barn doors to stay open -- nothing happens although I hear a humming sound as if the signal is being sent. During play, there were a couple of instances when the doors did stay open, but I'm not sure this was right either. The coil was a little hot, but the wires yellow/violet, and yellow are connected well. Has anybody had a similar experience or can recommend what else to look for?