Ah, there it is. What we used to call “bobbin art” in the costume shop, and what I just discovered online is called “birdnesting” by others. This happens when there is insufficient tension on the top thread to pull the bobbin thread up and out of the way, so it gets caught by the hook again and again, along with the later lengths of bobbin thread. “Insufficient tension” really means “no tension” in this case, so let’s have a look at the tension disks.
Yep, I missed completely. That thread should be one disk back from where it is.
Now, I’ve been sewing for well over 20 years and sewing with this specific machine for close to 15. This is just something that happens from time to time, and why we recommend completely rethreading the machine as the first step to diagnosing or solving any machine problem, “we” meaning us at the Sew-op. Learning to deal with these sorts of problems is the main benefit of Basic Sewing – thread gets caught on the presser foot. You catch a part of the fabric in your seam you didn’t mean to. Your seam line veers too far toward or away from the edge of the fabric. In the era of seam rippers, all are fairly quick and easy to fix, and if you want sewing to be a relaxing hobby I think it’s better to just accept the occasional necessity of ripping stitches. [Though thread caught on the presser foot typically just needs to be pulled out.]
In other news, I’ve decided to mostly depart from scheduled posts. I have one lined up for tomorrow morning, and I will try to post twice a week still, but I think it is silly to delay things I’m ready to show until some arbitrary time.