My conservatory double glazed doors have three hinges each and these are covered by plastic/nylon covers for aesthetic appearance. I removed these covers and found an adjusting screw on each hinge.It is necessary to adjust all three screws in turn to lift the door from jamming on the bottom rail - all three must be adjusted so no strain is placed on the door frame. It is similar to adjusting hinges on a cupboard door. Hope this helps.
Boatman 78, December 2009
