I had a small area that was sagging in my Monaco coach and I fixed it by heating the vinyl which apparently reactivated the adhesive. This may seem strange but I was told to use an electric heating pad, like you would use on your sore back to heat the vinyl. This heating pad gave an even heat that would not damage the vinyl. Give it a try and perhaps the glue that they used can be reactivated with the heat like mine was. If you have a larger area that is sagging, just move the heating pad around and do it one section at a time.