An employee was training a junior employee. They were troubleshooting an electrical exhaust fan. The system was locked out at the time. The employee began manually rotating the pulley via the fan belt. As the employee pulled the belt, he drove his left hand between the belt he was pulling and the pulley. This crushed his left-hand ring fingertip, including the tip of the fourth distal. He sustained an amputation of the fourth distal, from the nailbed to the fingertip.