Max certainly sounds like he is an Alpha horse.  It sounds like you should probably start him again from groundwork up.  I always like the John Lyons stuff.  His videos are really easy to follow and they teach mutual respect for you and the horse.  He has many things that you can work with when horses rear or buck, but you should start with the ground work first.  It is really neat when the horse "partners up" with you after your sessions.  I have done the Lyons programs with all of my horses and they are really great partners.  Star is still learning of course, and she is an Alpha Mare, so I really have to establish respect with her.  She still tries to test me sometimes and I have to let her know right away that this is not acceptable.

(I wanted to use this emoticon...it is funny)

Don't take this badly but it is a little hard to give advise on how to train your horse when you as a rider or even horse person need to be trained as well. This is supposed to be a broke horse, is it not? If so, then you can look at other things like equipment. I susspect his level and yours don't match...yet. Sure horses, like people, have bad days. Regardless you have to be the one in control. You have to gain the horses respect so he can trust you to be in control. How do you that? I can't just tell you with words. As I said, you need to be trained as well.

OK, tangible advise. Do check the saddle for fit. The bars may be pinching if too small. Also, if nobody there is qualifies to make sure the bit is working correctly then try something else to see if there is a change. Same with the saddle, you might be able to borrow a different one to test. Way too many things for here and now.

Dave