Hi Folks,
The fuel filler flap fell off my daughter's Mk4 Golf. I am left with the flap with Z-shaped spring attached, and the plastic fuller neck surround. It appears there is a pin of some sort which goes through, and the two lugs on the end of the flap hinge pushes back.. but will not stay put.

Does anyone know the trick of how it is assembled?

Thanks and regards,
Rob