check the hose and tubes are not blocked you can push out a blockage with a broom handle. I have taken the filters out of my dust manager as they restrict the airflow so the motor gets hot quickly but leave the filter in that is under the dust box as this prevents dust getting to the motor
Chris I, October 2007
It may be a defective thermal protector that protects it from overheating by turning off the vaccum if it overheats.
