I recently replaced mine. Couple of screws across the top, two on either side, and one torx in the back. There's a vent tube that you place in after the replacement, and the valve connection for this you have to transfer from the old box (this was a very tight for both the old and new box so be careful, it's twist-lock, a lot of wiggling and cursing). You also have to transfer the light assembly, which removes downward into the box.
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