Remove the (4) screws securing the air shutter bracket to the firebox. There are (2) screws on each side as shown below.
Once the screws are removed pull the air shutter bracket and venturi tube to the right side of the firebox out of the way.
Next, remove the light cover plates. There will be (2) on the ML39, ML47, and ML54 and (3) on the ML60 and ML72.
There are (6) screws that fasten each light cover plate to the firebox.