dash pad seperating

Back in 2007 I found a post about this problem. My wife's LeSabre dash pad is seperating. There is a hump from left to right for about 2 ft where the vinyl has I guess shrunk or pulled away from the frame where glued. I know I can pop off the metal plate that covers the width of the dash immidiately under and at the bottom of the windshield. Would it be reasonable to pull up the vinyl from the bottom of the windshield toward the steering wheel to the hump (about half the distance to the steering wheel) and then try to spread glue under the vinyl. The hardest part is the windshield makes working in that area difficult. I don't know if the vinyl rest on a solid frame or ribbed frame so I will make sure the glue make contact with the fram.