Your Balcony Doors
The doors to your balcony have an aluminium strengthener bar at the opposite end to the door handle.
This should not be used as a handle to slide the door, as I found out. The beam is there to weatherproof and strengthen our doors in the case of a cyclone, or strong winds. It is only held in place at the top and bottom by two small stainless steel screws.
I used it once too often to slide the door open, and the lower screw came out of its anchor point. Luckily I was able to re-attach the beam at the bottom by carefully locating the screw in its original anchor hole.

Alum. Brace Beam
The small stainless steel screw is at the bottom. Just under that is the hole for roller height adjustment.