Start backing out the top screw to check for rust on the screw stem. When you get to the 1st one with rust that will be suspect. Make sure the caulk on either side of the track is in tack. Believe me you can't over caulk a TT.
I have had more problems with leaks on my JFlight G-2 than I care to remember. My unit is a 2009 and in 2012 Jayco rebuilt the front end structure due to concealed water intrusion. Replaced all the struts and all new metal plus one piece from the front corner back to the slide out. I dropped it off at the factory in IN. It turned out to be a good experience as Jayco did it on their nickle as they could see it had been leaking since it left the factory.
Concealed water leaks can lead to extensive damage. Amazon sells a Moisture Meter for less than $20 bucks and it is worth every penny it cost.
My unit is exposed to the elements 24/7.