Possible the seat bottom hinge to the seat back frame is broken or loose? RICK
Fold the seat forward and send another pic of where the top and bottom of the seat meet together.Try putting new seat back stops on. They stop the seat upright portion from going back too far.
Alway need pics. I had set similar to those in a 69, the actual steel frame inside cracked causing it to lean when sitting against it. Had to strip the cover and foam off and weld her back together. Also replaced the stops.No more lean.Yeah maybe I hope he sends some more pics. I am curious to see whats up. RICK
Mine were not adjustable just a piece of rubber block type. Over the years had been worn down to a 1/4" new ones were like 3/4 and not petrified(sp) hard like a rock.I'm thinking thats whats wrong with. But I forgot about those rubber adjustable seat back stops. I had the same seats in my 35 chevy.
Yes tahat's another opition to shim the back of the seat track between the floor and seat track. Problem with this is it might take 1 or 2" spacer to get the seat were you want it. Kinda cheesy way to go. But loosen the seat up and give it try.could it be an issue where the rear bottom of the seat needs to be spaced. Area from floor to seat mount flange? as these seats were not made for this car and the floor pan that they were might have been different.