I have a 2004 Fleetwood Bayside. It appears that the roof has been leaking - there are wrinkles on the ceiling, rust in one of the lights, and mildew around the perimeter of the ceiling. There are mold/mildew stains on the canvas, which have been there for a few years. (I tried scrubbing it, using Dreft as the instruction manual says, but it didn't come out.) I want to sell it and am wondering if it's worth replacing the canvas and repairing/replacing the roof, or should I sell it as is for a lower price? Can I seal the seams on the roof without causing more damage by trapping the moisture inside? Thank you!