Ok so me and my parents jut went out to view a potential new horse. He was great in every way except he couldn't stop mouthing on the bit. I mean it was non stop! And not just a little bit of mouthing. Huge great big yawn like mouthing. He used to be a driving horse so isn't that used to having pressure on his mouth. But anyway, any ideas how we could stop this? Thanx for any input.