Those refit scan be found at Home Depot. I like those fans for certain vent duties in structures, but we recently refit a Panasonic in the place of an identical one to what you show and it's wonderful. You cannot hear it operating.
As others have said, lack of continuity with good spinning points to thermal fuse. Why? Who knows why. I'd suspect some bad insulation or a high impedance conductor in there for some reason.
Take the opportunity to put in a Panasonic as others have said. It really is a good decision if it's a commonly used bathroom that gets a lot of showers taken in it.