After a chipper knife change in the wood yard, employees were rotating the chipper disk to measure the knife clearances. To perform the measurements, the chipper disk is manually rotated to each knife location. To rotate the chipper disk, the injured employee placed his right foot on the card breaker for leverage. The employee's foot slipped and was caught between the card breaker and the feed chute resulting in an avulsion to the top of the foot and two fractured toes. The employee was hospitalized.