I found this by accident while searching for the source of the water in the holding tank bay. There is an inspection cover on the front of the shower pan with four screws. I removed the screws and that exposed the drain trap. There was water in the pan under that drain evidencing a leak. I had this same issue with the 2005 coach but it was much harder to access. I used a large pair of channel locks to tighten everything up and it is leak free now.