The cause of this problem is a worn out bottom door hinge. The bushings or whatever in the hinge are shot. First, we unscrewed and unclipped enough fasteners from the wheel-well liner to peel it back over the tire. Make sure door is closed now.
Old hinge comes out pretty easily.
Chisel off as much as you can of the seam seal stuff. After we mounted the new hinge we screwed the fender back, but it took a few small adjustments of screws to line it up. The hardest work about this part is scraping away the seam-seal stuff. This is where it becomes useful to have an auto body guy around. The cutout end hooks onto the 'catch' on the door frame, and the sliding gadget hooks into the 'latch' opening in the door.