He moves good and forward for about 10 minutes, making contact on the bit and making progress. After we've walked and trotted in each direction he begins to require a ton of leg and shortly after that he will all together decide to take 50' to move from a walk into a trot and buck, crow hop or generally throw a fit if you really press the issue (which I do, because he is not intimidating anyone and knows better!) when he does trot he'll duck behind the bit, refuse to bend and basically make you work for a really awful trot. He is not sore, or tired. I have had two instructors out and both left with a "That horse is a @!$#%&**" attitude. I am planning to get a few lessons with a Grand Prix level rider at the end of this month, to see if she can lend any advice on how to over ride this and generate movement.
Until then. What do you do in this case? What is the best remedy for a horse behind the vertical that stops with more leg? Any exercises that I could try to keep him focused and change things up? Its seems like the more I drive the slower and more resistant he will get. Also, I keep very light contact on the bit. I am looking more for his hind end to push him forward than I am for any "head set" or "frame".
What are good balance and straightness exercises?
I really do not have any current videos but these two pictures are a couple of weeks old. He was behaving, more or less, during the photos but maybe they'll help with any advice.