Hi Ivo,
I am not sure whether you ever received a reply to your post. I have only just seen it.

Your first question is really quite complex and I am gathering that what we think we are doing and what we are really doing can be very different (to quote tiger woods “feel and real are often not the same”) Therefore I can only tell you how I feel it but others could well have a very different experience. Over the last few months a couple of “ah-ha” moments for me were when someone showed or talked about a visualization of adding tension at the aperture corners by placing little pegs there BUT the tension is put there buy a horzontal and for me it feels like a slightly forward movement, like occurs when we say OOHH as Greg talks about.

Your second question about mouthpiece placement is that yes, the mouthpiece should be placed exactly where the visualizer was placed. Pretty sure of this from having and watching Greg’s lessons.

Now the 3r question. So when I get it right, it seems like the milk spout is taking most it not all of the mouthpiece pressure. So the movement mentioned above is for me, mostly the bottom lip coming forward. When it works the top lip vibrates with no problem.

Sounds to me like you are on the right track.

Cheers
Dennis