If you can take some measurements of the fan, perhaps it would be possible for you to buy a replacement fan meant for another machine that has similar dimensions to yours and swap it in that way.
Usually the motor is permanently attached to the frame of the fan but you should be able to pull the blade assembly off. Perhaps what you can do, is find another fan with a similar blade size, that also has a metal plate backing, and perhaps cut the excess off the new one, cut the motor coil bit off the old metal plate, and somehow install the new metal plate onto the old one.