Cause:  Air is going across hole

Remedy:  Blow more into hole

Cause:  lower lip not on hole

Remedy:  place more lip on hole

Cause:  corners of lips not pulled together

Remedy:  more "Whee"

Some Sound, mostly air:

Cause:  "splitting" the tone

Remedy:  Lowe chin, blow down

Cause:  Too large an opening in lips

Remedy:  more "oo" needed

"Woof" sound

Cause:  No tongue being used

Remedy:  Emphasize "Too"

"Thu" sound

Cause:  tongue going between teeth and/or lips

Remedy:  More "Too" (tongue on the roof of mouth)

High Pitched "whistle" (overtone)

Cause:  too much air

Remedy:  blow less hard

Cause:  head joint rolled in too far

Remedy:  turn headjoint out

Cause:  hole covered too much

Cover less hole

Flat pitch

Cause:  rolled in too far

Remedy:  roll out.