This has been a problem with many convertibles with glass rear windows that fold into tight spaces. One problem is the weight of the glass is only being supported by less than 3/4 of an inch of mating on the four edges of the glass.
One problem I've seen on Sebrings & Mustangs I've rented is when the top is down, the bottom of the glass where the curtain is attached has such a strain from the window being pushed so far back into the top well, I think from the constant strain on that mating surface the bond is eventually broken.
In the 60's the glass was Dielectrically bonded to the window curtain. Not sure what it meant - heat sealed perhaps??
When I owned a 68 LeSabre convertible, 4 shops said the back glass could not be reattatched to the window curtain. I was told this in 1986.
These newer cars might be different though. If your separation can't be repaired, I don't think you'll need the top. I'm pretty sure a Camaro has a separate window curtain that attaches to the last bow and connects to the body around he top well.
Lower the top part way and look in where the window is attached over the back seat. Have a friend sit in the back seat.
If you look inside the top material where it wraps around toward the glass, If you can see your friends head and can reach in and hit him, the window curtain and top are two different pieces. The top material essentially lays over the window curtain when the top is up.
One other piece of advice, If your car is driven in the winter don't run an ice scrapers along the very bottom edge of the glass. The edge of the scraper will go between the curtain seal & glass.
Good Luck.
Harryface =D8=BF=D8
1991 Pontiac Bonneville LE 301,311 miles