When I had my 68 LeSabre convertible the term in the Service Manual said
the glass was dielectrically bonded to the window curtain..

One of the hard parts about trying to reglue a window back to the
curtain is the amount of dirt & crud that got under the top material.
Another problem you've got to deal with is the weight of the glass
hanging on the material after its glued. If its done wrong - a few up &
downs of the roof could separate the glass from the curtain again. Some
tops when folded down there is such a strain put on that area along the
bottom edge of the glass that the seal eventually breaks loose. I've see
this happen more so on Chrysler Sebrings and Mustangs too.

Another thing that puts a strain on that area is temperature. Put the
top down when its 70 - 80 degrees out with the sun beating down on the
top - thats fine. But go to raise the roof  at night ( dark ) when its
60 degrees out that top material is now cold and has shrunk up so when
you raise the top you sometimes have to strain the motor to get the
header bow to touch the windshield header so you can lock the  top down.
WHen you pulling on the top to get it to go more forward, guess whats
holding back, the window curtain because the material is to cold to
stretch.

I've had no experience with this type of problem on the two converts I
had, but probably the best way to repair it is to remove the rear window
curtain from the top frame and work on it off the vehicle.

That also means removing the rear portion of the top from the frame. It
gets very involved especially if you've never done it before. The top
around the body line is tacked into strips underneath the molding. If
there is a tack strip in the third bow of the roof then that has to be
resealed when the top is re-installed or you'll have water leaks over
the back seat.
One thing is to make sure the inside edge of the curtain that contacts
the gas has to be CLEAN.

During installation of the top, the top has to be heated, stretched then
tacked so you get a smooth fit ands avoid wrinkles.

If you want to tackle it go ahead, but this is one area of auto work
that is best left to a professional. Its expensive work, but thats one
of the pitfalls of owning a convertible. It just depends how much your
willing to spend on a 8 year old vehicle.

If you decide not to fix it and you live in a cold weather climate the
rain & snow getting in the car will lead to high moisture in the vehicle
- thus causing the inside windows to fog up.

Good luck.

     Harryface    
05 Park Avenue, 32,062
91 Bonneville LE  304,345