1965 Valiant bench seat seatback issues

You're simply going to have to get the covers off and inspect it. It's not going to magically somehow fix itself, no matter how bad you want it to. I would be hoping for that too, if it was mine, because it's going to be a little bit of a pain. If you're careful with those covers, you can get them off and back on without damage. Let me get out to the shop in a few and I'll get you a picture or three if Vixen's seat backs. Give me a few. Coffee ain't kicked in yet. lol