1970 gmc Ingition switch installation

[cobra]

All,
I am newbee to the forum and this is my first time posting.

I am having a heck of a time installing a new ignition switch into my restoration project. I completly restored my 70' and am now in the process of putting it all back together.

For the life of me, I cannot get the tumbler to stay in the newly installed switch.

The Switch is plugged into the harness, spacer backs up to the back of the dash, I installed the bezel (remembering that the tumbler came out first).
But I cannot put the tumbler in and remove the key to finish the installation.

I need your guidance.

Thank you in advance