Howard,
I believe there is a strong possibility that you have some damage somewhere. The nature of how these are held in place almost dictates that. Somehow, of course the possibility exists that the lowest vane has pushed out somehow with no damage anywhere...
See the attached photo; unfortunately it is only of one side.
From this photo, you can see that on one side here, the side in view, the vanes are held in at two places: one, by a "rack" that has them all moving together. There is a "pin" cast into the end of the vane that slips into this rack. Below that, another cast-in pin slips into a hole in the sheet-metal base, and is held in place by an extremely complex bent spring wire. On the opposite side, another pin rests in a "boss" on the sheet metal base, and it too, is held in by a similarly complex bent spring wire.
For a vane to pop out, something broke, like one of the cast-in pins on the vane. Or, somehow the wire let go at this point. However, if the wire let go on the far side (the side of the assembly not visible in my photo) I would expect more than one vane would have come off.
In any case, I hope this helps you understand what you might be looking at when you attack the problem.