Our first suggestion is the obvious: Before doing anything, get those rollers replaced. Most major hardware stores will carry a wide variety of replacement rollers that will work for most any modern door. In order to replace these, you will need to remove the operable portion of the door. You may have to pop off a threshold cap that holds the door in place to free the door from the opening.

As far as the threshold is concerned, we have some wonderful news for you! The folks at Blaine Window Hardware Inc. in Hagerstown, MD, have a product called Pop Track which is a nylon patio door replacement track. We're told the product comes in 8-foot lengths and can be cut to length upon request. You can contact Blaine at (301) 797-6500. They also have a catalogue available that features 800 of the over 20,000 replacement parts they have available for windows and doors.