Ok, made some headway.The lock cylinder seems fine. All detents are in the switch. The lock is on the right side of the column, the switch is on the left. A rod connects the lock to the switch-it runs through the column and has a large oval cutout on its right side that engages a matching lug on the inner end of the lock cylinder. The left side of the rod engages a keyed slot in the inner end of the switch. I took the switch apart and see no damage-no significant wear, no cracked or broken pot metal or plastic. I shaved a little plastic off the cam in the switch to allow the start contact (#50) to be engaged a little early. The car starts and runs, but you have to move the switch back just a little to fully engage run position (#3). That cam was what moved the switch back to #2 (with pressure from a spring in the switch). My dilemma is still what to replace? Looseness in any of the connections between the end of the lock cylinder and the switch could explain my symptom. I see no wear or cracks anywhere. The rod that runs through the column may or may not be one piece-there could be slop there if it's two pieces or more.