Will
Being the curious sole that I am, I took it apart to see how it works. From the first picture, you can see a small brass plunger that comes out of the turn signal indicator. On the back side of the white ring, is a brass circular plate. Once the turn signal part is installed, that plunger engages the plate. The small wire that Mark found, is inserted into the white column on the steering wheel side of the white part which completes the circuit to the horn. The clock spring is not needed.
For those who have this column, I encourage you to clean the old grease and dielectric contacts since the grease is old and non functional. If anyone has taken the column completely apart to get at the bearings. I would like to know how you did it.
I spent a few minutes cleaning off surface rust and repainted the unit to spruce it up a bit.