2005 W900 with the 72" sleeper, the windows on the sides at the top of the sleeper are leaking. This happened two years ago, I woke up one morning with a wet head, pillows and mattress. I caulked the windows and frames with windshield adhesive, that has worked until two days ago. I can't get up there to see if it has cracked or started to pull away. But when I get home I want to pull that stuff out and use something else. What should I use?