Insert an object such as a small slotted screwdriver into the BLADE SCREW (5). Rotate the BLADE SCREW counterclockwise and remove it. Slide the blade away from the UPPER GUARD and remove the blade. Slide a new blade under the UPPER GUARD with beveled edges facing you. Align the hole in the blade with the hole in the blade shaft, insert the BLADE SCREW and screw it clockwise to secure the blade tightly.