When repairing your damaged sliding glass door, start by removing the door from the track. Slightly open the door, hold both sides firmly and lift it. Remove the door by pulling the bottom towards you till it is off the track. Use a brush to clean the track. Use a vacuum cleaner to remove the debris. Measure the track guide, and cut a length of track cap for filling the door opening, then set it over the track. Tap the cap lightly from one end to the other using a rubber mallet. Finally, replace the door.