Yes, contact Canvas Replacements. They were very helpful with our first popup, I did have to send a pic of the original rail since there had been a couple of styles. Since the pup was so tiny, they offered to cut the rails into a shorter length to save shipping. There was only one run long enough to have to butt ends of the new rail. Bear Creek Canvas probably also carries it.
If you contact either, give make, model, year, and VIN (helps confirm things), and maybe email a pic too.
Thank you for your prompt reply! Another problem. When I put the door down on my Viking SAGA 1906 Model 2000 Tent Trailer, I need to crank the trailer high and it has a tendency to pull the door side canvas panel from the upper mounting track. I have considered lowering that track to allow this not to happen. One of the reason I was seeking a new track was to attach it so that the lower track might give me some extra length. Don't know if that explanation makes sense, but it is a start. I guess I could also lengthen the canvas in that area, but that would mean I would have to get some extra (about an inch) of canvas on that door side canvas panel of about 8 inches. It would seem there might be a better solution. Common sense about these type of issues isn't so common to this POP UP newbie. Thanks for any ideas from anyone! Nice site with which to share ideas. Mike