Thanks for the Accessory Manual link and pictures, Bill! I've been wanting to see the Assesory Manual. I'd like to find a pdf download of it to keep on my PC with the other manuals I have. It appears though, the Manual has a different style mechanism than you and I have. Ours is the same as that linked assembly picture in my first post.
I've noticed in your picture, your cancelling plate edges also registering on the roller bushings! I think that discovery will really help me. I'm just glad I didn't break that cast metal cancelling ring by tightening down the shoulder screw too much! I realized I had a problem and backed off!
Great that you remember the thin strip! I didn't mention, it also has a notch on each end... I'm not sure of to clear screws or to help lock into a position somewhere.
Like you, it being thin might lead to think it has a spring or retainer type function.
I didn't help that I also placed my column shift assembly parts in the same baggie... I somehow don't think this strip is affiliated with that but I've been wrong before!
Jerry