The flap wears right where you have got the nut.
The nut is probably too much, i usually put one or two washers in there and you need to file off one side so they will fit up in there.
On that model/type if the door is too far over to the left the edge of the door will not sit in the keeper inside the catcher.
Theres a knack to putting the catcher on one of those.
Is the thumb catch working right? Just flicking the door up with the thumb lever on the RHS should make it snag on the thumb catch. The bump in the leading edge on the catch tab is meant to hook under the bar on the door.
