some of those spools are weird -- if you are rewinding the film and it refuses to pull out, don't force it. Take the back off the camera, remove the film and takeup spool, cut the film leader off where it goes into the takeup spool and pull/push the stuck bit through and out the other side.
i have a IIa and, yeah, the takeup spool is pretty cheesy/cheap plastic. If it were to break, you could easily replace it with the spool from a reusable film can, some of which had slots to insert film. Worse comes to worse, you could tape the film end to the takeup spool, or even use a second film can and just wind it can-to-can.
That's actually why those and Exakta cameras have removable spools -- to allow you to take it out and just wind the film into a second can. It made reloading faster for professionals in a hurry. Exakta even had a film knife to cut the film end off so you could switch the now-empty can over and use it for takeup.