rotors don't just break, you'd have to smash it into the ground to get it to stop working. just replace the stator and you should be fine. it probably just shorted, that's why it smells burnt. it happens from time to time. sometimes the varnish on the windings just gets old and brittle, and when it starts to come off, it shorts out the stator.

did you check for continuity from each leg of the stator to ground? if there's continuity there, it definatly shorted.