I own a 2011 21mb and the awning on mine is a 15' Dometic Sunchaser 2, model 8275000.401B
I'll bet mine is completely different that yours because of the age difference, but maybe that will help. I recently tore the fabric on mine and it was pretty expensive to replace. I also found that many parts are not available at all, or the price is so high that you'd be just as well off to buy a new one. You might start here in your search:
http://edometic.com/allusr/sp.nsf/cv?openview
That is the Dometic parts website. Good luck!