Is it possible that something is borken in my drivers seat in my 2002 XJR?

The right side of the seat back feels (and looks) as if it not supported and is trying to recline.
If I sit behind it in the back seat and push it forward again just on that side of the seatback, it seems to fix it for a short time.
What the heck can it be?
Thanks for any input.

 

The adjustment mechanism could have jumped a tooth. When you adjust the seatback does it stay at the wrong angle, yet continue to adjust?

 

Yes sir, it does.