Try rotating the collar on the column counter clock wise and try to rotate the key again. As stated above, you could also try removing the actual ignition switch from the column to see if the rod will have a full range of motion when turning the key to the different positions. I had this same problem many years ago. I just can not remember exactly what it was, but I remember me saying to myself, silly me. It was something very simple that I was doing wrong. If I remember correctly it was that the arm on the end of the column was in the wrong position. To correct that rotate the collar on the column counter clockwise. Is the column out of the car? Could you have a non tilt ignition switch? They are different than what is used on a tilt column. When I say ignition switch, I do not mean lock cylinder. One time I had a problem with the pin that locks into the lock ring to lock the steering wheel in place. I think the problem there was that is was rusted in place and was not able to move in and out. Not sure if that was part of the problem that I had that was similar to the problem like you are having, but it did cause some issue for me.