Range hood impeller slipping on rotor shaft
Put a drop of super glue on the bare shaft, then slide the impeller fully into place. Put the nut on without gluing it. Leave it for an hour so the glue can set up. You could also use a threadlocker liquid on the shaft. I have repaired loose impellers for combustion air fans inhigh efficiency furnaces. I also use this repair for bath fans and rangehoods.