Don, I have the same model/yr. as you. I had some leaks around the baggage doors. Check very carefully to see if yours leak. If so, I can detail a very simple repair procedure to stop it. Perhaps it is leaking somewhere else. I also installed a fantastic fan to replace the wimpy bathroom fan. This significantly reduced the musty smell (and other odors as well) in the camper. Also, make sure your kitchen sink air admittance valve is functioning properly. This can cause a musty smell from the grey water tank. They go bad occasionally, but are not expensive. Let's keep dialoging until you find a fix.