When I try to buzz on the mouthpiece......nothing happens. I have tried pulling the mouthpiece out of the lead pipe while playing a note with a hope that it will buzz.......nope. Sometimes I get a sound, but it sounds more like a dying duck. For the mot part it is a quiet "whoosh"ing sound that comes out. As soon as I start slowly bring my finger over the end of the mouthpiece to creat a little back pressure.....viloa! I can buzz. I do play 2/3 a rim off center to the left....could this be the problem? My range is descent - I can play the 1st C above the staves with little or no issues during practice or piece playing. I've been told by other brass players that I have a good tone and clear. Play a lot of duets with another trumpet, we are able to blend with the odd issue here and there. I have tried other sized mouth pieces still no luck ( 1D, 2C, 1 1/2C, 3C, 5D, 7C there are a few more but I can't remmber them) Even whe I was trying out different cups and back bores with the Warburton rep....still no buzz unless there was some back pressure. Is this something I should worry about or just go with what I know works? Help.