Jim,
Both of the 32 ADFA's I have: the choke plate shaft looks like this:
http://www.flickr.com/photos/bigtimes_fiat/3261997556/ the shaft is machined at the end with the parallel/square sides, the small tab also has square sides so there should be no movement between the two. With the choke plate all the way open = vertical, the machined sides of the shaft should also vertical. Your picture appears that the choke plate is all the way closed. Are you sure the movement is at this point? Hold the choke plate closed with you finger, then try to push down on the tab. If the movement is there you can do like Mark said and place a spot weld there, or if you don't have a welder carefully drill or grind a notch in the tab right next to the shaft, then peen the shaft into the area to lock the position. Support the opposite end of the shaft as you hammer or you will drive the whole assembly through the carb throat, or crack the throat housing.
The second picture is the choke unloader cam, not the fast idle cam. If you got the carb off the car go through all the adjustments and checks in the workbook. The movement of that stepped cam is dependent upon the wound spring in the automatic choke housing. Either you don't have the automatic choke housing mark indexed with the carb body, or its simply not cold enough for the spring to retract and completely close. The indexing marks should be aligned like this:
http://www.flickr.com/photos/bigtimes_fiat/3261217645/ Also make sure the notch on the choke housing is engaged with the spring. If its not engaged the choke plate will just flutter and not spring back closed.
