Not sure you understood my recommendation–it was to spend some time with the horn where you place your lips to the mouthpiece as Greg describes, Mmmmmmwwwwwaaaaahhhhhhooooooo, perhaps more of a “forward” embouchre than what you’re used to (than what I was used to), with the sensation of OOOoooooooooooooooooohhhhhhhhhhhhhh (tightening the corners).

I recommend trying octaves low G below the staff to G on the staff to G above the staff by just tightening (slightly, only as much as needed; be willing to miss the note), then A…

I felt how little incremental effort the G above the staff is than the G on the staff is…

Then I moved to A… I think you’ll experience what I did–a revelation that the A is right there just by tightening the corners slightly, it’s not hard and requires no kick of the air or tilting back of the head, rolling in of the lip. It’s just right there.
And that B is only 2 half notes above that, and high C is only 1/2 a step higher…

For me, that was the big reveal that led me shortly thereafter to playing my first ever High C.

I’ve been having great sensations lately, this morning was great–seems like Double G is becoming part of my useful range now and I’m moving up to A natural, which is only a stones throw to Double C–my ultimate goal. I think my ultimate goal would be to “own” a Double C, nothing higher.

Now, when I play/practice, I don’t get tired to the point that I start losing range anymore like when I was in high school / practicing a ton. Now, my new way of playing seems more efficient and effective where I’m not tearing myself down anymore but am building myself up.

Looking forward to seeing your post when you have your “coffee moment” as Greg describes… Keep at it, it will come in only a matter of a short time…if you let go.