I only use Connecting Threads Essential thread on my Brother XR 9000. Everything else screws up the tension or gets tangled. I have no problems with Essentials - have tried the Gutermann, Coats and Clark, and Star - just won't run smoothly. Maybe you should try...

I've discovered a couple of things that cause problems for me...when I get to sewing too fast then stop abruptly the thread will somehow or other end up wound around the spindle the spool sits on and when I (Miz. Oblivious) start stitching again the top thread stretches too tight and breaks, causing the needle to come unthreaded. Or if I forget to be sure both top and bottom thread are under the presser foot to the back when I start a seam, everything balls up at the edge of where I'm trying to stitch and it won't move forward at all.

Good morning, I relate totally to the time with our grandchildren. Nothing else happens when I have them. Those moments go away so fast I want every one I can get while they are there. It takes me days to recover when they go home because I am worn out! I am glad you had a wonderful time.
mom-6, my sq9000 does that dance too. Makes me feel like I have been slapped in the face sometimes because it happens so fast! I am glad you mentioned it because I didn't cover that in my trouble log for Dee's friend.
Mary, I think the tread is a huge factor but haven't been able to isolate to the fiber of the thread. I am sewing with thread that is very linty (used to make uniforms). Now that I know not to pull the bobbin thread out of the thread path and to pay attention to the top thread wrapping around the spool stick I haven't had any problems. I do clean my feed dogs and bobbin case holder frequently. When they get linted up they get a stomach ache!

I had the same problem (E6, clunking, etc...), for the life of me couldn't figure it out. rewound my bobbin tons of times. finally walked away.

Came back to it the next day and it was the stupidest thing ever. The thread was miswound inside the machine - not down by the bobbin but up top. So, I undid the top thread and rethread it through the machine and all was fine. has been fine since.

kclausing, you say the top thread was 'miswound' inside the machine.
Do you mean it was 'misthreaded'?
If you do not mean it was 'misthreaded' please go into more detail on where it was 'miswound' inside the machine and 'where' inside the machine it was miswound.
If it was miswound your explanation will help us problem solve on craftiladi's machine too. Thank you so much for the help. It is much appreciated.
Regards, Dorothy

Yes, I meant misthreaded. But not that I misthreaded it. The thread came out of the slot in the arm that goes up and down (sorry I don't know names of parts), but it caught on something inside, so it was not noticeable. I had to look close to see this. This was causing my tension to be inconsistent, thus causing my issues.

Okay, that is very very helpful. ((I think mine has done this a time or two also!. Thank you, it gives us another place to look. Very helpful.
Regards, Dorothy