Sounds like there is a bit too much upholstery in there after the re-do.
There is a screw hole in the bottom, but it's covered by the leather, and difficult to find. It's nothing fancy, just a small hole for the self-tapping screw to fit. You may need to pull the leather back from that area to find the holes. Then you can get a better idea of how to position the seatback. I've had the back off a couple of times, and it's difficult to get pushed back to align the holes, even with the original leather.

DG