Everything that was said in the post above, and...
...you are playing behind your fulcrum on the left hand, which is probably the biggest contributor to the poor technique.
Once you turn your palm in instead of up (which will actually allow you rotate instead of lifting your left hand and also allow the contact of your finger and thumb to remain), choke up a little less than an inch with your left hand and angle the right down more; you'll notice a difference in sound quality, more control, a faster feel and more than anything a more consistent hand-to-hand sound quality.
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It is my preference to teach this way, as some will argue otherwise, but I believe that the fulcrum is in the same place on the stick for both the left and right hand. One last thing- your left hand should be wrapped around the sticks when you bring them in- the way you have it now, they'll fall out of your hand if the wind blows too hard.
