Sliding glass door repairs are not as difficult as they sometimes seem. The biggest problem is with the lack of available information on how to perform repairs.
The most common sliding glass door repair is replacing the rollers. Rollers on sliding glass doors wear out through use and because of debris caught in the track. To repair the rollers perform the following steps.
Step 1 - Clean the track
Before removing the sash, make sure to clean the track thoroughly to eliminate any possibility that the malfunction is not due to foreign objects, rocks, or dirt on the track. Use a stiff brush to loosen up any dirt and a vacuum cleaner to suck up loose debris then spray WD-40 on the track. Use a pick to clean off the stuck-on debris and wipe clean. When you are finished, the track should be spotless. If the door still doesn't work properly, you'll have to remove it.
Step 2 - Remove the Door
Remove the door from the track. This varies from door to door but typically involves sliding the active sash to the center of the frame, lifting it up and off the track from the bottom. Some light door models such as screen doors use rollers at the top with adjustment screws at the top to hold the door in place. With heavier patio doors, you should get help for this step.
Step 3 - Take off Rollers
Take the rollers off and take them to a local hardware store. Match them up with new rollers. You might also check online where there are some suppliers for rollers.
Step 4 - Install Rollers
Install the new rollers on the door and reinstall the sash to the door frame. Finally, use a screwdriver to adjust the bottom rollers so the side of the sash comes parallel to the frame, and to eliminate any drag it may have against the track, and do the final adjustment of the top rollers if any.