The door need " Toeing and Heeling "
I had problem with website,so copy & paste it to here
PVC-U doors are heavy, and although the dead weight is supported on the hinge side when it is opened, there is nothing on the lock side to support the weight, and without the procedure of toeing and heeling the door will drop on the handle side, sooner or later. To stop a door dropping the glass itself has to be braced diagonally corner to corner by the insertion of plastic packers slipped in the gap between the glass and frame, under the beading. On the hinge side the packers go at the bottom corner, whilst on the lock side, the packers go at the top (opposite) corner, get it?
How to Toe and Heel a door, properly:
1. The glazing beading must be removed first, and the double glazed sealed unit must be in its place, and resting on its plastic setting blocks, for correct drainage to work properly before beginning the procedure.
2. The opening door leaf must be raised on the lock side to the desired height, to square it up again. For one person to do this on their own; open the door slightly, place a small piece of wood on the floor to use as a fulcrum and in line with the door.
3. Next, place a plank under the lock side of the door to push down on with your foot to raise up the side of the door that has dropped. A word of warning: Some doors will rise up and come off of their hinges, and these are harder to "jack".
You should notice a gap between the sealed unit and the door, and this is where the packers are inserted to achieve your toeing and heeling correctly to brace across the glass to stop the lock side of the door dropping out of square.
Also see
this from previous post