I've got a 1971 Cutlass and the ignition lock cylinder would not allow you to turn the vehicle off (unless you used pliers). So, I decided to replace the lock cylinder, and I can't get the cylinder out. I've followed the manual, but when I look into the vertical slot there isn't anything to push in. It looks like I'm looking at a side of the steel cylinder. On my new cylinder lock I can see the spring loaded mechanism that I think I'm supposed to be pushing in on the old one. Nonetheless I can't get it out. Any thoughts?

 

This is covered pretty well in this link.

Bottom line, try the hole just to the right of the hole you have tried so far.
Personally, I recall that the hole you have been using is the right one, but, as in this picture, this guy had success with the next one over.





- Eric