I found this for you...hope it helps. The only problem would be if the furniture is warped and the opening has tightened on the glass.

Smoothing Your Sliding Door Track

By
DoItYourself Staff

When a sliding door track gets gummed up and dirty, it can make using the door a hassle and a pain. In order to prevent this from happening and becoming a problem it is important to not only get the track clean, but also to lubricate the track so that it will slide easily.

Cleaning the Track
Cleaning a sliding door track can be accomplished through several different methods. The first thing you need to do is remove all the dirt and grime. You can do this by using a multipurpose cleaning spray. Just spray it into the track and leave it to soften any accumulated dirt. Once it has been on the track for about 30 minutes or so, come back and attack it with a toothbrush and a soft cloth to wipe up the grime as you move along the track.

Another approach is to first clean out the track with the vacuum cleaner. Most vacuums have a crevice attachment that can be used in the small space of the track for your sliding door. After vacuuming, then take a small whisk or other similar brush and vigorously brush away any remaining dirt and grime.

For stubborn bits and pieces of dirt, you may find it necessary to take a nail or other tool that can be used to dig into the dirt and clean out any small holes or crevices in your door track that are designed to allow water from the outside to drain from the track to the outside. Once you have dug this type of dirt up, you may decide that it is best to either vacuum it clean or follow it with a cleaning solution.

Whatever your cleaning approach, first make sure that the track is clean and dry before you move on to applying a lubricant to help the door slide better.

Lubricants
Once you know that the track is free of debris and dirt, then you are ready to begin applying a lubricant to the sliding door track. The most popular lubricant for this purpose is WD40. This is a common lubricant that contains light mineral oil and mineral spirits.

Another popular method of lubricating and smoothing out a sliding door track is to simply spray a light mineral oil directly on the track and slide it back and forth until the lubricant has been fully distributed along the track.

You can also carefully spread petroleum jelly along the track with your finger or a small brush and then move the door back and forth to distribute it along the entire length of the track.

Finally, an eco-friendly green approach is to spray or spread a small amount of fish oil along the track and run the track back and forth until the track slides smoothly. You can purchase fish oil at most health food stores or in the pharmacy section of most drug stores of grocery markets. Fish oil does not smell “fishy” and is inexpensive.

Summary
If you sliding door is not sliding smoothly along the track, try cleaning the track first and then applying a lubricant along the length of the track. Soon you will have it sliding smoothly again with a little effort.

Read more: http://www.doityourself.com/stry/smoothing-your-sliding-door-track#.UIQWqoZfHbg#ixzz29wrdX4HJ

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[ Edited by: VampiressRN 2012-10-21 08:40 ]