I bought a like new Yamaha YBB 105 3/4 tuba. I "played around" on a normal size tuba before and was able to hold my own. I used to play the trumpet. Amateur level on all. I have had the Tuba for about a month and play it nearly every day but for the life of me, I can not get a C3, B or Bflat below C3 to come out of this horn. I can play notes below and above. I can't imagine it's my technique since I've been struggling for weeks. Please help.