Hautau Lift and Slide door in E16 Royal Docks is tilting. When the door is closed there is a gap towards the bottom. Also the door is dragging making it very heavy to open and close. This is because the innermost runners are lowered and causing the door to be unaligned. 

The runners need replacing so that the door is aligned and straightened which allows the bottom keep on the frame to engage with the door locking mechanism. This will then get rid of the gap and stop the door dragging when opening and closing.