I have a Fusion, but I have a friend with an HQ 16. We were having all kind of problems with her machine, and finally turned the needle just a teeny tiny bit and it worked.
When my Fusion came back from a different dealer she had really messed up my tension. I was not impressed. I tightened the top tension all of the way. Lowered it 4 turns like I had been told, and slowly one turn at a time lowered it more until it worked the way I want it.
Also, the videos on the site are really good. I got them on a dvd with my machine and have watched them several times.
If the thread is popping out of the upper tension it will also cause big problems. It has to be in really tight. Mine had never done this until it came back from the other dealer.