I've been working with my new Baby Lock Jazz 2, trying to do both free motion quilting and template quilting.
After each little bit of work, I would remove the quilt sandwich and look at the back, only to find top thread in the back. This happened every time, and I finally realized it was only happening on the curves. I had kept adjusting the tension to remove the problem, but never could get rid of all of those bottom problems.
I finally browsed around the internet to see what was happening. I discovered that what is happening is called "lashing", which happens when you go around curves too quickly. Solution according to the writer is to slow down on the curves.
Since I don't have a speed adjustment for my machine, I can't just mash the pedal all the way to keep a constant speed, and thusly, only have to concentrate on how fast I move the fabric. This is going to take a lot of practise.
If I can't do two things with my hands like when I have tried to play a musical instrument, I will be stuck with straight line quilting. I've never been able to coordinate my two hands to do two different things at the same time. Had this problem my whole life, other than I finally learned how to touch type, so maybe there is hope if I persist long enough.