I think I'm inclined to agree w/ the training issues. I would not just "hit the rail" when you ride this horse. I would get on and before even asking to walk I would do some turns on the forehand and some hindquarter turns. Then I would do small circles and serpentines at the walk and trot before asking for the canter. This sounds like he needs to pay attention to you and settle down. Definitely do not hit the rail. Keep this horses mind going at all times, do trotting poles and tons of directional and transitional changes... Do not give him time to think....
"Be a best friend, tell the truth, and overuse I love you
Go to work, do your best, don't outsmart your common sense
Never let your prayin knees get lazy
And love like crazy"