What was the problem? I checked my tension, all was well. I switched from a universal to a sharps needle. None of that helped; the filmy stretch silk I'd chosen for the body of the garment, while beautiful, was just too flimsy to stand up to my machine.
The simplest solution is, of course, to choose hardier textiles that are easier to work with. But how could you resist this gem of a piece (bought on extreme sale as a 2-yard remnant at Britex)? So. What to do?
These sorts of situations call for a stabilizer of some kind. Some people might use interfacing, as in the collars and cuffs of a garment. There is also stabilizing fabric like that used in embroidery. But both of those things can be pretty expensive if, like me, you are having to use a bit in almost every seam of a garment.
So, as a thrifty sewer, I use plain old tissue paper. Tissue paper is wildly useful in the sewing room--you can use it for this, to make additions/changes to patterns, or just to write down notes on the fly and slip them into your pattern envelope. For stabilizing, just cut a piece of tissue wide enough to cover your seam allowance plus a little more on each side. My pieces were about two inches wide.
Place the tissue between the layers of fabric you are sewing together, or, if basting or finishing an edge, place the tissue on top. This will give the needle some substance to hang on to, and stop the tension of the thread from snagging underneath your work.
Then, put the whole shebang through your machine. And then go slowly. Start off about as slow as you think you ought to, and then slow down a little bit more. It took me roughly three times as long as it usually does to piece this garment together, but the decrease in frustration was worth it.
When you're through, you'll have a nice seam with a big piece of tissue paper running through it.
Open the garment up and pull the tissue <b>gently</b> off one side of the seam. The second side should come off quite easily now that it's not attached to anything (the needle cuts a nice perforated line through the paper at the seamline).