I ordered the fabric from
http://www.toughtopawnings.com They have very good videos for the Ascent fabric removal and replacement. Cheaper than Carefree and they claim their stitching is superior to what Carefree uses.
Carefree of Colorado has a service manual for the Ascent slide topper that describes everything.
https://www.e-carefree.com/ecarefree30/product-library You need to confirm you have the Ascent model awning. According to the document you put 11 counterclockwise turns on the right hand awning end (the end with the spring) for this 165" length. You use a 3/8" ratchet and extension and have someone hold the dead end of the roller tube. Once the 11 turns are applied, you pin the awning end with the spring with a cotter pin or a nail to keep the tension on.
You ultimately attach the new fabric to the awning rail of the RV and the roller tube you have sitting on top of the extended slide. You then roll up the excess fabric, remount the roller tube into the ends, install the retainer washer and screw on each end, then remove the pin. Let the fabric roll up tight. You need two ladders and a helper.
Sounds more complicated than it is...it's a very simple mechanism. Just be careful if your awning and roller tube is still under tension. Mine was not since after it separated from the RV it rolled up completely around the roller tube.
Sorry to hear you are winterized already. My two bedroom slideout toppers show the same signs of fatigue in the stitching so will be replacing them soon.
What really bothers me is that I've never heard or seen anything describing the need to periodically clean the debris out of these slide topper assemblies. I just cleaned out the two bedroom ones this morning and am amazed they didn't bind up with all the debris around the ends and the roller tube. I always wondered where this debris goes, boy I know now! Think it should be a yearly maintenance item, mine went for 5 years accumulating debris. I always thought it self cleaned/fell out the bottom somehow, boy was I mistaken!