I bought and had the new Legendary gator top installed on my car afew years ago by a professional upholstery guy. Within 6 months it started to loose adhesion to the roof is small spots that eventually grew into larger areas. Most seem to be around the perimeter and not directly in the center area of the roof. The upholstery guy is standing behind his work and his initial thought was "bad glue". Now that the replacement top is ready to be installed, we don't want this to reoccur.

Here's a pic of the roof before install, and of the vinyl top letting loose. You can basically peel it back by hand. What prep should be done to the roof before install and has anyone experienced this issue? Any recommendations on glue?

Thanks
Tom