Apparently, I'm not the only one who has had problems with the end pieces of the awning poles falling out and getting lost. I tried to find a replacement for them, but finally gave up and made my own. I haven't tried them out yet, but I feel pretty confident that they will work as least as well as the originals.
I've attached a picture that shows the original pieces in the poles and my replacement (both in and out of the poles). Hope this helps someone.