We were having a problem with ours retracting. Got to the point where you had to push up on the arm to get it to come in... and when it finally DID come in, it wouldn't completely "click" into place. You had to give a push forward on the front-most arm to get it to snap into it's final position.
After thinking about it for a long time (and struggling with it that whole time), I realized that if I had to push forward on the front arm to get it to finish closing, SOMETHING must have been pulling backwards on it. Took a close look at the awning fabric and realized that the fabric had slid forward on the roller arm, but the fabric attached to the roof hadn't. So it was creating a slight backward tension on the whole setup. I got up on a ladder and, with some help, managed to get the fabric slid back into place on the roller... so that the edges of it went straight up to the roof - perpendicular to the side of the coach.
Ever after, the awning has worked perfectly.
Not sure if I was just lucky, or what... but you may want to have a look. Cheap and easy fix if it's your problem, too!