Well, after continuous fighting for years against my 6X8 hfgh door, I finally followed the advice of someone here on the forum and applied a coating of silicone grease to the runners on the door. Guess what happened! Instant easily sliding door. I've been thinking about this for a long time and finally got the grease at an Ace hardware store today. It took a few minutes to apply, but made the door slide more easily than ever. It will be interesting to see how long it holds, and how often I will have to reapply it, but for now I'm quite happy with the results. Jim