Fix the exhaust fan to the ceiling. Coupled with the ambient temperature, the temperature of the motor will be 80-90 degrees, which must be hot. This is normal.
Generally speaking, as long as the temperature control element in the motor is effective and exceeds the warning temperature, the exhaust will automatically stop running. I dropped my belt. If there is noise, add some oil.
Solution: Dismantle the motor, polish the rotating shaft with fine sandpaper, fill the bearing and linoleum with high-quality lubricating oil with high temperature resistance, and try again.