how to work adjustment screws on kawneer door

I have a Kawneer door that on side is down. There are two adjustment screws, but they don't seem to do anything. How are they supposed to work?

Ok, the problem is solved.
What I did not understand is that out of the 3 holes (and screws) in the sides of the door (see earlier picture) only the CENTER HOLE was an adjustment. And that screw is at least 5 inches into the door frame. The top and bottom screw is to secure the frame together.

I removed the door, removed and cleaned both roller assemblies, cleaned the track, re-installed the door, and adjusted the rollers using the center screw so the wheels supported the door, and have about a 1/4" gap between the door and track.

I still have two questions..

1. What is the part number of this roller assy. in the picture so I can order it in the future?

2. I have another door (same type) that is missing the threshold (see picture). How can I order that.

Please include the cost of both items,

Thank you,

I have a 20+y/o Kawneer 60'x80" sliding glass door which is in need of it's rollers replaced. The original rollers attached to the slider with two screws on a tab at the top of each roller. It seems that all of the suggested replacement rollers don not have this attaching tab. Any suggestions would be extremely helpful !!