I’m no expert and learning this myself but for what its worth this is how I buzz the leadpipe. I don’t play with lips forward. I think this is more of an exercise to get a feeling of engaged corners with the centre of the lips relaxed and open. If I am wrong I am sure Greg will correct me. This is how I do it. First I put my lips together in there normal relaxed position with my teeth aligned and slightly apart. No tension. No smile. No pinching. Then I let the centre of the lips open slightly and engage the corners. This feels like the lips are in a position to cool soup. This engaging of aperture corners feels like an inward movement. Now place the mouthpiece on these relaxed lips. Take a relaxed breath and just release air through the lead pipe. Don’t try to make a buzz. It should feel like your doing nothing. Do this again but this time slowly engage the aperture corners more and an effortless buzz should just happen. At first forget about the tongue. Just do breath attacks. The centre of the lips remain apart in the mouthpiece no touching. I hope I haven’t confused you and this description of my setup helps.