MikeR,
Did you check the individual wires underneath the Drivers bottom seat cushion?. Mine had broken over time and the abuse of offroading. I heard them break (Bionk!) several times, But didnt put 2&2 together untill I had to have the seat adjusted all the way up! I thought I was Shrinking!.
The wires are easy to replace too. I also use some Cheap-o Carpet for a Barrier between the spring wire net and the foam, because the wires were cutting into the foam bottom.
I hope this helps!.
BTW, If you reach under the cushion and can grab lose wires on the seat bottom, The wires are broken, Remove 4 bolts and the cushion comes right off!. Then just pry the plastic c-channel off of the seat frame and the foam will be exposed, Lift off the foam and you can see how the wire framing is put together.
I hope this helps too!
Doug.