1962 220 Sb Fintail - Dreaded Blower Motor Replacement

[Vancouverfinnie]

Well - the bad news first, the blower motor needs replacing in my fintail. The good news is, I have found a good working replacement. I need the blower, not so much for heat, but defrosting. I bought the entire heater core and blower motor as one unit - but need to pull the blower motor out. I cannot figure out how to do it, but think I need to pull the plastic fan part off first, and underneath that, there are probably a couple of screws, so I can pull the whole motor out, and then drop the working motor it (I will probably do the brushes while I am at it). Anyway, the little brass/metal nut on the top (it had a funny name in the parts book which isn't in front of me) - doesn't seem to want to turn, in any direction. Hopefully someone knows the trick to this (it isn't a screw, and is not a bolt, but a round pin-type top to it) - hard to explain. The orginal parts book I have shows it, and it looks like it is threaded, but I don't want to force it one way or another for fear of snapping it.

Any information anyone can provide would be most welcome! Thanks,
Rory