A friend has a PVC exterior door in the kitchen, on which the upper hinge centre pin has a habit of rising from the hinge, which is the top of three such fittings. When it first occurred, the door lock was refusing to engage, and I rectified the problem by tapping home this offending pin. That then aligned the door correctly. I did notice that it has lost its plastic top seal, but assume that to be a dust cover.
Since then this pin has needed attention about once a month. Should there be a circlip at the bottom to hold the pin in place? And why would it tend to rise, defying gravity?
DJ