bobbin shank might need a good clean; bobbin maybe not wound properly, also needle could hv hit something on the bobbin shaft (this can happen if you manually turn the wheel backwards)& pearced it causing a catch (hope you understand what I mean); to be on safe side take machine to dealer & get it checked they should be able to help (hopefully it will be a simple remedy). Good luck

My Baby Lock was doing the same thing...I changed the needle and PRESTO!!!

Does this happens when you are using prewound bobbins?*****

hi if you have a thread cutter just check that it is going all the way back as this was the problem with mine

This kept happening with my Brother, and it turned out that the tension was all goofed up inside. Apparently the needle had broken a tiny piece off the bobbin case and messed everything up. Take it to your dealer to be checked.

that is what happened to my Brother 4000D.. took it in and got it fixed .. now it embroiders almost better than when I first bought it.. that was only little over a year ago .. that was the second time it was serviced for the same problem.. I purchased a 4 year contract for it and I will take it in every time it gives me any kind of a problem.. so take it in..

Mine did THE VERY SAME THING!!!!! I had a little piece of a needle in there that was shreading the thread, breaking it ect. After that was removed, a new needle put on and PRESTO good to go.
I also clean out the bobbin case frequently. all kinds of lint and thread pieces can get in there and create nightmares. Also a broken needle can create a burr on the thread plate.
Hope this helps hon.