Same set up, same problem for me.
Even after I took the machine off the frame and used to do my quilting on the table, I still had problems.
Someone suggested that I use titanium needles. I just picked them up the other day. Now if I can just figure out where I put them, I will give it a try.
Try to adjust your tention.
Lower your threadstand so that the thread isn't whipping out of there so fast.
Slow your machine down a bit, I have it set right in the middle at the sitting rabbit.
My thread used to break whenver I would start quilting towards the left but adjusting the tention helped.
Make sure that you only use the HL x 5 needles as indicated on your machine.
I hope this helps. I feel your pain and frustration.
I think I might have even had a crying fit or two.
Carole