http://www.youtube.com/watch?v=Q1mRhcquZTM
Awesome! I had always been told to NEVER touch the bobbin tension. And then I got a long arm. Out of sheer frustration and at the end of my rope, I checked the bobbin tension and found nearly all my problems. I do the drop test as well, and am thinking I still have it too tight.
I never thought about checking the tension with the changing threads - great point!
Thank you for posting this. Again, Awesome!