HOW TO USE THE ONE DOOR SET PROCEDURE The HavaHart 1040 (and also the 1030) are designed to allow you to use it as a one door set.  This can help you to catch a larger and/or quicker squirrel that is escaping your trap and your best efforts. LOOK AT YOUR TRAP If you examine the rods that control and connect to each door, you'll note that one door has a straight rod and the other door has a curved rod.  Lock the one with the straight rod in the closed position, be sure to lock down the door with the wire bail that secures the door.   Place the bait all the way at the closed end of the trap so that the animal must crawl across the bait pan to get to the bait, thus springing the one open door.  You might want to insure that he can't get to the bait from the outside by placing items beside the trap so he can't reach through.  On the outside, we use wooden boxes, open at each end, but you can use something such as cinder blocks to block his access.   Bait the trap with the bait of your choice, or even better, HIS choice.  If he has been taking some kind of food stuff from you, try to use that to attract him into your trap. Have patience.  It may take awhile, so use your head.