Wipe both the seal and the door dry. Then take some petroleum jelly and put a thin coating on the seal. Now, close the door. reopen the door and inspect the portion of the door on which the seal is 'supposed' to contact. If it is not making a good tight seal, at any spot along the sealing surface, there wont be any sign of the petroleum jellu on the door. Also, see if the width of the transfered jelley is a uniform thickness, any spot which is narrower than others is getting less seal compression, and not leaving as much petroleum jelly on the door.