I agree with Terry. In order to make a serious attempt to flatten out the cardboard, you need to remove most (if not all) of the upholstery. If the warped area is only in the bottom few inches, you might be able to back up the panel with some 1/8" plywood, and staple, glue, or sew both pieces together. You have to keep the reinforcing piece 1" or more away from the edges, or the repaired panel won't sit tight to the door. If the warped area is is in a larger area, or the entire panel, you might as well just replace the board, as you'll probably find it's a lot less work.:anim_25:
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