I agree about there being a steep learning curve with tension on LA's. One of the big things is that you need to adjust bobbin tension for each thread, something we rarely do with domestic machines. I struggled and struggled with tension for my HQ until I bought a towa gauge and put a digital readout on my top tension. now I have very little in tension problems. I never could get a good feel for the drop test, and never could remember which way to turn the dial to increase/decrease tension. Now I set my bobbin at 200 and adjust the top tension to balance, and I'm good to go. Top tension will vary between 550 and 800 on my gauge, so that is quite a bit of variation.
Then add in the tension problems that are due to the tension on the quilt sandwich - What I can say, quilting is so much funner after I figured out all this. You could say the problem was both machine and operator. The machine is particular, and I had to learn those particulars.