Just to be clear:
You should be able to remove the entire window from the fiberglass body. There is likely leakage between the aluminum frame and the body. You can re-seal with 3/4" butyl and re-install.
To fix leaks
between the aluminum frame and the glass pane, see my previous post.
Just FYI, all of the windows
in my 1979 Boler
1700 leaked in various ways:
- Between the fiberglass body and the aluminum frame
- Between the aluminum frame and the glass pane
- At seams in the aluminum frames, for example, at the aluminum frame butt joints
- Also, rainwater can back up over the window tracks into the trailer if the tracks are clogged with dirt and debris, so clear the weep holes and tracks.