So I lost my only key today on my 1971 cutlass. I have read the forums and read my factory 71 manual and none of it has showed me exactly where to push the pin to get the key cylinder out. I have a picture of what part of the metal that needs to be punched out with a thin blade screwdriver. Don’t understand why the factory would do this and leave it sealed off. It makes even an experienced car guy like me hesitate to start punching screwdrivers thru the face but worked great once I did. I kept the ignition in the locked position and depressed the pin while prying on the ear of the switch till it popped out. Now the blue arrow is where I punched thru the first time and it only shows you the end of the key cylinder. The red arrow shows you where I used a very small thin blade screwdriver with a heavy hammer and just tapped it thru. There you can see the pin!

 

It's just casting flash, a normal byproduct of the die casting process. Never made a plastic model? they have the same problem.