How do I get the turn signal cancelar plastic piece out of steering column

I finally got the ignition tumbler out. It is jammed and will not turn with key in it. Is there some way to see if its the wrong key? Previous owner says it is but who knows. Tried all the keys. Also, the round headed key don't open the trunk. If not there are plenty of them for sale on E-bay. Anywhere else to buy one? Also, I think these can be refurbished. Any way to take it apart and see what is jamming it up? Any way to get a new key for it to ensure the key is the right key before buying a whole new ignition tumbler? Their pretty cheap but I always like to try to fix something if I can.
That link to the '72 FSM explains how to remove the cylinder w/o disassembly of column. Look for a small notch beside it and release with a small screwdriver. Love those FSM.

IMG_5998.JPG

IMG_5999.JPG

IMG_6000.JPG

IMG_6001.JPG

IMG_6002.JPG