Brad, the Boler
17 window seals / gaskets are still available. See the following thread from a few months ago for details:
EDIT (fixed link):
I recommend you remove all of the windows
from the trailer in order to re-apply butyl tape to the back of the window flanges, as this is a common source of leaks
The 70 feet of 1/8" glass glazing bead (H009-344) around each pane of glass does NOT actually seal the glass, but it covers the sharp edge of the glass, keeps dirt out and helps hold the glass in. What really holds the glass? Where the back edge of the glass pane rests in the frame, either 1/4" wide butyl tape or 1/4" wide polyurethane glazing tape or glazing silicone is applied.
But first the frame must be completely cleaned and all previous sealants removed...
Good luck with your project! You will enjoy the results.