1946 Super 6 Heater motor fan removal

I am working on the heater box in my 4 Super 6, and the lead wires to the motor have no insulation left on them, so I need to open the motor up and re do the wires. Step one seems to be to get the fan off of the shaft. Any tricks to that? It seems really flimsy and I don't want to ruin it.

Thanks! dan