Hey Thom, be sure to watch the early videos over and over and over.  Eventually the note will speak naturally.  Your lip oscillation isn’t yet 100% sympathetic, it is taking time to respond to the change in air pressure, that’s OK, stick with it.  I suggest lots of visualise (or finger), tissue, mouthpiece (no buzz) then add leadpipe practise and simply keep doing the correct PROCESS, don’t manipulate it.  Cheers, Greg