If the lock core has been pulled and use of the guard key has not opened the door, then it is time to apply the DP-7B Door Puller Set. Place the stepped Spacer Block onto the hook unit. The 3 different diametered steps of .345" (2.15cm), .562" (1.43cm) and .680" (1.73cm) make it adaptable to 3 different sizes of plug holes. Place the correct diameter step into the hole. Have the hook end set against the inside back wall of the door, then tighten the knurled nut to hold the hook in place. The flat surface on the outside of the hook unit should be in a level position.The long flat blade is then fitted onto the holding slot, along with the remainder of the Puller unit, as shown above. Position feet away from the centers of adjacent doors,to minimize the possibility of distortion. The knurled knob is then turned until the door is pulled out.