hey so im trying to take out my headliner due to that it's sagging from the leaking sunroof. of course i will fix the sunroof first but taking the headliner off is puzzling. i have all the plastic molding off around the headliner but the thing wont budge. it seems to be glued to the ceiling. its the 4dr tahoe LT w/ power everything. any advice would be most appreciated. thanks.