I have found them to be a little different from year to year. I have a 94 and it is a little different from my friends 98. You can by the nylon "thread" from sewing shops or if you can use a green thread, I can, you can go to your local tackle shop and buy some nylon braided fishing line. It is about 10% of the cost of sewing material and much stronger. Get a pencil and paper when you take the old line out. Draw yourself a diagram. The smaller shades have the line on the outside edges, the bigger ones have these plus one in the middle. I have not seen a diagram posted of how the line goes. The do unsnap at the top from the track and you can use a sewing bobin to hold the line at the bottom. The line does have to be pulled tight. Not snug but tight when you reinstall. Hope this helps some.
Keep the shiny side up.
WBCCI # 348
Past Region 3 President
Past President Tidewater Unit 111
Rick Bell in "Silverbell"