Vic it sounds like the PDO is not square but sometimes these things can't be found. It may be easier to just fit a door spring to the operator. Its shaped like a crocodiles jaw opening with the top tip over a little. You attach a roller to the car door and when the door is fully closed the roller is in that little tip over to hold the door shut. If you want i can send an attachment with a drawing showing what i mean. You could also attach a spirator as well.