Ignition lock cylinder will not turn to lock position

Two months ago my alternator went out on this '96 Cavalier 2.4L convertible and I had to have it towed home. When the tow driver turned the ignition on to turn the front wheels and place the transmission in neutral and then attempted to turn the key to the off and then lock position, the steering wheel would not lock and allow the key to move to the lock position and thereby release the key. After the 45 mile drive with the dying alternator and the resultant 45 mile tow with the key "on," the battery was all but shot and I disconnected it until I could engage the repair. I finally replaced the alternator and thought the key may have been stuck due to damage to the Passlock security feature on the car. The kicker is that the car will crank and drive with no security feature hindrance to starting or driving; the key does move to the off position and stop the engine. So, I am at a loss what to do now; I have suspicions but need better advice than the local parts' stores. Here is what I have done:

1) Removed the entire lock cylinder and tumbler assembly. Upon removal the tumbler assembly rotated properly in the lock cylinder and the key released.
2) Removed the tumbler assembly from the lock cylinder.
3) Cleaned and lubricated with graphite-laced lubricant.

When I reassembled the entire mechanism, the steering wheel still would not move into the lock position and release the key. However, the car would still crank and drive and when you stop the engine, the accessories, and thereby the batter, remain operational.

Looking for suggestions. I have tried an alternate key and moving the steering wheel back and forth.

Thanks!