Pete, what I actually suggest is long tones and lipslurs after learning to breathe properly. With a decent daily routine, the mouthpiece gravitates to its most efficient position. The biggest problem in this thread is placing intellect before practical experience. A very good place to start a beginner is in the middle. When you have them on a decent daily routine, most things solve themselves. Fixing DIY chops is impossible on the internet. Even if the mouthpiece is placed in the theoretically correct place, we still do not know how much pressure is on the upper and lower lip, the angle of the horn relative to the teeth, position of the tongue in the mouth, quality of breathing, body use, tension, brain power in use while playing. I have crooked teeth and used to play with the horn pointing to one side - I never thought about it, the mouthpiece pressure probably was most evenly distributed that way. In the late 90's I bought a Monette horn and mouthpiece and changed concepts. I did not ever consider changing my embouchure, it just happened slowly and naturally. I first noticed years later after seeing some pictures in the newspaper. Now the horn is pretty much pointed straight - not necessarily my recipe for anybody, but my natural "best".