I've had this problem before, replaced the key mechanism about a year ago, and now it did it agian. It's a '65 Ranchero with 289 and C4. I can't figure out why the key keeps getting stuck in the "run" position. It won't unlock (turn to the left to the off position), but it will turn to the right (start position). I've done everything I can think of, replace the mechanism, dielectric greese, etc.

The key has unlocked (turn to the off position) on it's own, previously, but I can't figure out what prompted it to unlock. However, it seems that it's just a matter of time until it's stuck agian.

Very frustrating!

What is the cause of this? Is there a fix for this problem?