window caulking??

[Brian Hobin]

Hello,
the curved dark plexiglass or plastic window covers over the front windows of our 94 Excella are out of the aluminum frame channel on the bottom of the frame. I worry about water getting into the channel in the winter and freezing. In order to repair this, should I take the whole curved plexiglass panel out or can I simply lay a bead of something over the outside surface---if so, what stuff? Advice would be appreciated.
Regards
Brian