What type of motor is it? I recently repaired the controller for an old Craftsman Bench Grinder, which operates on 120V AC single phase. It has a speed controller circuit using a Triac as the switch (and DIAC trigger), and applies a full wave rectified line voltage to the motor. The motor is rated as 1/5 horse power. At low speed there is hardly any torque at the output shaft. I thought at first that it is a Shaded-pole motor, but can't confirm that from the outside. It has two brushes contacting a rotor.