Got it apart, finally. I don't know why, but the flange came apart from the pulley and the belt slipped off. I don't understand why the flange is separate, anyway. Why is it not just a one-piece pulley? I pushed the flange back on with a hammer, as it is an aluminum piece, instead of the plastic one. Searching for an aluminum one, now. I hope it lasts a little while longer, until I can find one.