My back has been "thrown out" for about 4 weeks, so I finally got a chance to get up on the ladder and attempt to move this.
It did not move. The front edge, where I was pulling, slid about an inch, but the entire awning did not slide, it simply stretched from about the middle forward, remaining uneven at the rear end.
BUT!!! The awning closes now, the arms line up, and close again, so I am happy about that.
I may try again on a rainy day, and see if the rear end will move. If not, I may try a silicone-based spray lube on the rear half of the grooves.
FWIW, I have two of those screw-down de-flapper thingies that snap onto the fabric, and has two velcro loops that I can wrap around my wrists, to pull harder without putting too much pressure on the fabric. See below. They really helped get a good grip!