I have a used dash pad air bag cover for the Volvo 850 cars. It is very common for the dash pad to curl at the air bag. Most of the time the air bag cover curls. I have not been successful in getting any type of adhesive to glue the cover vinyl down. However, I have managed to replace a air bag cover before. Remove the dash pad, remove the air bag, and replace the cover. Care must be taken to do it successfully.
The cover I have is about 30 years old to my knowledge and probably has cracks on the underside plastic of the cover. The cover itself, top side, was lying flat and in very good condition when I pulled it from the vehicle or dash pad. Pictures are below.
NON-refundable. I do not want to anyone to return a damaged cover