Step 2 · Access the Plumbing
With the water off, you must now access the faucet's plumbing. Locate the access panel on the wall of the tub surround or an adjacent wall. These panels may be held in place by screws, clips, or simply pressure-fit. If screwed in, use the appropriate screwdriver to remove the screws. Carefully pry the panel open and set it aside. Use your headlamp to inspect the plumbing, familiarizing yourself with the hot and cold supply lines, the valve bodies, and the connections leading to the spout.