Series 860 bits can be converted to series 859 by changing the bearing to 1/2. Important: always assemble the black bearing heat shield with the raised side up when changing the bearing. Improper assembly will cause the screw to come loose and the bearing to fall off when working. Spare Parts:
791.002.00 Bearing 3/8
990.057.00 Screw for Bearing 1/8W X 1/4"
990.422.00 Shield for Bearing - I.D. 5mm x O.D. 9mm