AC Riser Gap with Roof

[stiks471]

I am going to redo the Dicor on the AC unit. There is a fairly large gap in some spots, , at least 1/4 inch, between riser and roof. It feels like there is some “hot glue” or similar adhesive that was used at the factory. It’s the gray/clear stuff attached to the underside of the riser. Should I try to reglue the riser down before redoing the Dicor? I thought about maybe putting window foam seal in the gap as well so it’s not just all Dicor. The trailer is two years old but appears to have been stored uncovered outside.