EE WAS RE INSTALLING A RETURN ROLLER ON A CONVEYOR APPRLX. 32 INCHES FROM THE GROUND HE WAS UNDER THE CONVEYOR ON HIS HANDS AND KNEES. AFTER INSTALLING THE ROLLER. THE CONVEYOR WAS LOWERED INT O POSITION. AT THIS TIME, THE ROLLER FALL OUT OFONE OF THE BRACKETS AND STRUCK EE ON THE FINGER.