The only thing I have to share is an epiphanic revelation, and yes, epiphanic is a real word. About once a year I "get" a dressage idea that once realized seems so straightforward in its simplicity that it makes me wonder how I can be trusted to walk and chew gum.
Now that we can at least get a canter on the correct lead, I am working on refining and smoothing out the canter that follows. It may be a canter by definition, a three-beat gait performed by a horse, but there is nothing controlled about it. It is wild and wooly and difficult to maintain. As we pass by the gate/rail/open end/etc., Izzy's shoulder bulges out and we can't make the turn.
No matter how hard I pull on that outside rein or counter flex him, we can't make the turn, so he either slams to a stop or falls into a washing machine trot. Fortunately, he's an equal opportunity "shoulder bulger" which means that it is happening in both directions. It seems to happen mostly as we are approaching the gate end of the arena, and for what it is worth, I NEVER finish our rides at the gate or even looking at the gate. He simply knows where the exit is.
The next day, my entire purpose was to move the shoulders in and out. I started from the walk tracking left then right and all over the place. I didn't stay on a circle, but rather moved his shoulders around no matter which direction we were walking. In a very short time, I felt him get really supple in the bridle and knew that I was on to something.
When we picked up the trot, I focused on keeping his shoulders straight, not his head and neck. And suddenly, I had a different feel in my hands. It very nearly felt as though someone actually smacked me in the head.
When I felt like he was between my reins evenly, I asked for the canter. It was still wild and crazy, but instead of focusing on where his head was, I kept his shoulders even, right between my legs. To the left, he was able to make the turn almost effortlessly, and I was able to start pushing him over onto the outside rein.
To the right was a still a struggle, but I think he finally started to figure it out. I worked really hard to keep his shoulders square which meant that it felt like I was riding in a counter bend. When I finally felt him rock back on his haunches and lift his shoulders in the turn, I brought him back to a walk and gave him tons of praise and quit working.