This is not Jayco specific but might be of help to others. A friends Class A had one none opening window in the back of the slide and no window to the front. We measured the existing window and ordered two windows from Rv Windows, Windows For Rv | Motionwindows.Com
The company was really helpful in getting the correct measurement for the custom windows. The windows arrived two weeks ahead of delivery date.
Next step was a template of the cutout, locating & marking the area on the slide. Next was drilling a hole to start the jig saw and making the cut for the window. Next was 1" wide window caulk on the outside window edge, place in the cut out. The bezel is then placed inside the cut and screwed in place. Trim the caulk from around the out side. Done!
The non opening window was removed using putty knives to break it loose from the slide and saved. The window replacement was as above with the opening enlarged slightly for a new larger window that opens.
The wall was fiber glass outside, 1" Styrofoam fill and wood panel inside.