HOW TO FIND THE COMBINATION ON A DUAL DIAL POST OFFICE BOX DOOR
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STEP 1 - Remove the gear cover on the back of the door, if present, by removing the 2 screws indicated with arrows
STEP 2 - Notice that there are 2 gears, upper and lower, and that each gear has a rectangular slot cut into it to accommodate the cam on the latch slider.
STEP 3 - Facing the front of the door rotate the left dial until the slot in the top gear is aligned with the cam.
STEP 4 - Again facing the front of the door, rotate the right dial until the slot on the lower gear is aligned with the cam.
At this point the door should open easily as you slide the latch on the door front, left center, inwards towards the eagle.
STEP 5 - The correct combination can now be read from the left dial to the right. The indentations on the top of the door over the center of the perimeter of each dial point to the correct letter and segment setting.