Step 8 · Create Drywall Access Panel (If Needed)
If your leak test fails and the leak persists, the issue may be with the connection of the pipe to the drain assembly itself, not just the gasket. Since you do not have an access panel, you will need to create one in the drywall on the wall behind the tub's plumbing. Use a stud finder to locate the studs on either side of the plumbing. Use a level and pencil to draw a rectangular access panel (e.g., 12x12 inches). Carefully cut along the lines using a drywall saw or utility knife. This will give you the necessary access to inspect, tighten, or repair the plumbing connections.