My diamond was doing this also. It was so frustrating and expensive when I embroidery. Everyone gave good answers. It may be the thread is coming off the spool too loose. I put the felt pad under my spool and the plastic top on it to keep it from spinning. If you are using large cones, put it on a stand behing the machine so it has more space to straighten out the loops as it comes off the spool Good Luck

It could be a build up of lint. Give your machine a good brush out and make sure the upper thread is sitting in the take up lever properly and not missing because it is too loose.

No Michigan cannot claim this one all to themselves, all though, I wish they could. I have had the same issues, and I live in Kentucky and have found at different times different situations is the causing issues; many of which have been mentioned on this post.

Sometimes there is a piece of lint in the bobbin case (just where the thread comes out of it) and that REALLY can cause problems. I try to clean out the bobbin case and that whole area before each project.

I just had this problem. I rethreaded the machine, checked the bobbin, neither worked, then I remembered I had adjusted the tension recently. Readjusted it one number at a time, was able to keep a beautiful even stitch while totalling eliminating the bird nest problem. Of course, I had thought the machine would need to go in for service, and every other wretched scenario my tortured brain could conjure, including multiple $$. It was such a simple fix and she is humming away once again.

If this happens to me I re-thread the top and bottom.

Mine was clunking and leaving a bird's nest also. I took out the bobbin reinserted it, cleaned the bobbin area, rethreaded the machine, cleaned out the top part of the machine. Problem solved. Don't know which part was the one that worked but I find it's always a good idea to do all four.

Thank you everyone for the problem solving--I knew this forum would have the answers. Now I need to get out my owner's manual for my machine since I still call certain parts "that thingy" or "gizmo" and correct the problem.

Paper princess is correct - it happens on my Husqvarna when the thread jumps out of the upper uptake lever. The machine even sounds slightly different, and I can tell much quicker now. Luckily its easy to cut the birds nest of thread out under the fabric piece and start over.

Try re threading your machine. If the problem is below the fabric the solution is above the fabric and vice versa. I have this happen to me from time to time and then I just rethread it and then take any pieces of thread out from under the throat plate and that normally fixes things.