How to Tighten Seat Screws in a 07 Tr186

Noticed my seat backs are getting a little loose. Would like to tighten the screws. Can someone tell me how to do this. I noticed that the center lumber support feels like it could pop out but something feels like its holding it on the top. Here are a few older pictures I had in my computer.
http://i218.photobucket.com/albums/c...1/S5000785.jpg

http://i218.photobucket.com/albums/c...1/100_0506.jpg

Anyone?

if you move the lumbar part where the crack is there should be some screws in there so that the center part pops out then the other screws are behind that part mine is doing the same thing but they won't tighten up due to possible being striped. I need to put in bolts and nuts on them but afraid to.