Thank you, I keep forgetting about Fenzi classes. I was looking at them a few months ago, for something else, and then it just left my brain lolLeerburg has multiple videos on teaching heeling.
I believe AKC heeling is a bit different some of the bitesport heeling. So if you want to compete make sure you are training the correct "heeling picture".
Fenzi Dog Sports offers multiple self study courses on teaching heeling. They also run various courses for Rally during their semester courses.