I have an HQ16. I used to have this problem until I (accidentally) stumbled on the solution for my machine. You may want to try this to see if it solves your problem. Thread the machine, then pull the thread through the top tension disks so they are secure. To make it secure, I grab the thread above the disk with one hand and then below the disk with another hand and pull the thread toward me and move it up and down between the disk a couple of times, thus securing it in the disk. Hope this helps.

I usually get these problems when I use different weight thread in top and bottom. I tend to agree with everyone else that it is a thread problem.

I forgot about needle alignment. Yup, that can cause it too.

This sounds silly, but - have you re-threaded your machine? I fought with my HQ16 for a full day and a half, then discovered that I hadn't threaded the top thread correctly! Believe me, I was relieved to find that out.

I've done that, too. It works.

Thank you all for your tips booked marked the Jamie wallen video..Slowly started adjusting tension and now i have beautiful stitches..Have a post it note to test tension on ever bobbin change and new quilt..
God Bless
Loretta

I have a Statler Stitcher and a couple of years ago I was ready to roll the machine out the door to the curb! For mine was doing horrid stitching also. I tried everything for days on end. Then out of the blue I changed bobbins, and it stitched just fine. On closer exam of the bobbin itself I found that it was out of round, and it was a brand new bobbin! So that bobbin went right to the trash. It could be something as simple as your bobbin itself.

I've not heard of bobbin genies before, just googled to see what they are, Do they really make a difference.

I use bobbin Genies in all my machines, even the drop in bobbins. It prevents static. If I don't drop them on my white floor they last almost forever. LOL

Not sure where thread mount is on machine. Try having it "take up" from a stand