Remove the door from the track.
How to fix a gap in a sliding glass door.
The door opening in the framing is not square.
How to fix the gap on your patio door duration.
You may like my other videos.
Buy new foam filled vinyl tube weatherstripping the press it.
This video shows you how to take apart sliding glass doors.
Simonton windows doors 102 622 views.
Then remove the door stop at the top of the frame which should be as simple as unscrewing it.
Gap between sliding doors doors cannot close properly.
This will retract the rollers and make the door flush with the track.
Pry out the old weatherstripping from inside the door frame using a flat head screwdriver.
It looks like the gap is caused by the hardware for this barn style door which is a common scenario.
In the picture you show you could place one piece vertically on the wall side of the door on the end the picture was taken.
For the best seal my recommendation would be some pieces of weatherstripping or gasket.
Sliding glass door adjustments.
Just type lsailor1 in the youtube search bar.
First locate the roller adjustment screws and use a screwdriver to turn the screws counterclockwise.