Then take a look at the upper thread path and make sure the thread did not pop out of a tension disc or thread guide. If all is well above the needle, look below the fabric and open the bobbin case. Often, my problem is solved at this moment – the bobbin is empty! That’s a simple fix with a fresh bobbin.
Often, lint or fibers get caught in the spring and it effects the tension on the bobbin thread. In fact, it’s a good idea to clean the tension adjusting spring every time you change bobbins.
Once it’s clean, reinsert the bobbin and check the stitches under the needle. Touch the needle advance key and go back to the last stitch that was laid down prior to the break. And believe it or not – those steps solve the problem – almost every time! These multi-needle machines are amazing.