2002 Chevy Blazer rear window suspension

Sounds like the nitrogen charge in one or both of the support struts has leaked out. The only way to repair it is to replace them. They are not difficult to replace, but they are not real cheap. To remove them you use a thin bladed screwdriver to pry the retainer clips free on the socket heads where they snap onto the ball stud glued to the glass. You will see a thin spring clip that goes around the socket. If you look in the pivot hole you will see the ends of that clip. Remove the clips with the glass supported securely. Clean the pivot balls with some scotchbrite or sandpaper and apply a small dab of grease. Then install the new supports. I don't recommend replacing only one support because the new one could have different properties than the old one and could twist the glass and shatter it.