I just took apart a 2005 leather seat. I would take the two plastic side covers off and see if anything is broken or loose. There are two big bolts attaching the back to the seat, they could have come loose or a bolt fallen out. To remove, on the cupholder side, take the two screws out of the cupholder, lift up and out to remove. Then lift the seat cover in the back to find the other screw attaching it there. There is another screw behind the lever. Then lift carefully while pulling toward the front to release it from the lip that holds it on the front. There is a screw up there also, I think. You will have to jockey it around the lift lever, don't force to hard or you may break it. Check the bolts. The return spring may be broken and jiggling around or allowing it to be longer than normal when folded. The back piece that covers the spring pops out. I would spray silicone on the joint before you try to pop it up, be careful. Rock it back and forth and up. The other side, inboard, is simpler, it has a couple of screws, but the front has a cup for a barb in the metal that secures the front. You must put the front on first when reassembling. After removing the screws, slide it forward to remove. Check the mounting bolts too to see if they have loosened. At this point you can take the seat cover off, with a little more work if you want to service it.
Hope this helps
tcwagner