Bosch 3107DVS Electric Sanders & Polishers "replace bearings polisher" Questions

how do I replace the fan assembly cannot hold armature assembly to get inner bearing out without damaging armature assembly If you are replacing the fan assembly because the internal thread that holds

...belt sander. they used to be metal but now they are plastic with no bearings, so im trying to find replacement rollers. We just picked up a new belt sander and I compared all that were on the shelf ...