My Excella had a very bad leak. Not able to locate the source, I removed the end plastic panal off the ceiling. Yes, that is a bunch of work. However, I wanted to find the leak and find the leak I did. The front top panel on the roof had no seal between the outer panels and water would leak in the length of the seams on both sides. The water would drip to the wires in the insulation. Travel along the wires (the conduit) and follow the wires to the wall on the road side. Then leak down the channel to the front window also to the floor on the roadside. I mistakenly blamed other sources because the water came out many feet away from the real source. Also, Vista View windows will leak, too. But the water from that point should go straight down to the floor. Not travel as would when you have a roof leak. Once I found and repaired the leaks then I have started, and am still working on, the repair of the floor and related areas. Good luck.