Door flexing

[Wgesnerjr]

My original door had this same issue. I remember seeing a "reinforcement" plate on the inside of the door skin. I had thought that plate might have a broken weld or something.

For other reasons I wound up using another set of door to finish my truck, but would start looking at the plate. the side glass was out of mine which made it easy to see it flex.

If there is some kind of weld that's broken, and rewelding is not an option...(like good paint on outside) I would look at something like JB Weld to reattach.

good luck.