Follow the steps listed below to attach the blade in the DW321 or DW933 jigsaws. Lift the black handle/knob approximately ¼". Turn the handle/knob counter clockwise 5-7 full turns until blade chuck is completely open, keep the black knob pulled up as you turn it. Insert "T" shank or universal jigsaw blades into the chuck making certain that the back edge of the blade fits into the support roller. Please note that when using "T" shank blades, insert the blade to the shoulder of the shank. With the knob/handle still in the up position, turn the handle/knob clockwise until the knob starts to ratchet. Make sure when tightening the clamp it clicks 3 times. Push the handle/knob down. The blade is completely installed at this point.