Before doing any major disassembly, check to make sure that the large Phillips head screw/bolt that secures the recline lever is tight. If that's not the case, remove that screw and pull the lever off and inspect it for damage. You may merely need to replace the handle.
The linkage that releases the mechanism allowing the seat to recline does not seem to be readily accessible with the seat installed in the truck. You may need to remove the seat and do some disassembly to get at it. Good luck. I hope my first couple of suggestions solve your problem.
RipVan