Over the summer, I had the saddle fitter check out my saddle, the chiropractor did some body work, and I had Izzy's hocks injected. None of it made a difference. By the fall, I was genuinely considering selling him. Nothing I was doing was helping him to relax or feel comfortable in his work.
Then he refused to take the bit for bridling. My trainer suggested we change bits, so I switched him to the Myler Correction bit and things started to improve almost immediately. After that we moved him into the double bridle which worked like magic, until it didn't. He had a major meltdown about that, so I went back to the correction bit.
Throughout the late fall into winter, the jackassery began to fade, and we actually started to make some real progress. At the beginning of this year, I moved him into a Myler ported bit which is almost dressage legal. Since then, Izzy has done nothing but be fantastic.
Now, rather than simply get control of a freight train, we are schooling movements from Training through Second Level. We have a decent stretchy trot, we can maintain the canter lead on a single loop, and he can even do a pretty nice little turn on the haunches!
I have a dressage legal bit ready to go, but since I don't have any shows lined up just yet, I am going to wait a bit longer before we transition to it. While he is super fabulous, he still has an occasional brain fart. The ported bit gives me the control I need, so that his shenanigans don't get out of hand.
I've always been creative with my bit selection, but after working with my big brown horse, I am an even firmer believer in adding a bit check when trying to figure out why a horse won't work for you.