The parking pawl on an AW-4 is actuated by a rod driven off the main selector shaft. The rod and pawl are serviceable after dropping the pan and removing the valve body. If adjusting the linkage does not restore "PARK" function, that's where I would head next.
1992 XJ 2" lift -- RIP
2000 XJ 3" lift -- Australian Ford Big Brakes up front, rock rails, ZJ rear discs (with WORKING parking brake), C4x4 rear bumper/tire carrier, Hella H4 headlights, IPF driving lights, OEM skid plates, OME springs/shocks, JKS LCA's, JKS Sway Bar links.