Remove Squirrel Cage from Blower Motor Help

Its a 1963 Valiant.
I am having a really tough time figuring out how to remove the, what appears to be, press on nut holding the squirrel cage to the blower motor. I would like to replace the cardboard gasket between the two. I took out the small allen screw, but can't get that nut in holding it on to budge.


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