My wife uses cone thread in her Singer 401A machines both at home and at the shop. The twist of the thread on the cone can cause the problem that you’re having, even when using a thread cone stand. She noticed it more at home than at the shop, and we finally figured out that she changes thread colors often enough at the shop doing alterations that the tangle doesn’t get big enough to cause a problem before that thread is removed and another color is threaded up. We’re not sure if it’s all cones, or just some of them causing the twisting condition. We haven’t taken time to study it that far.
There are a couple of things that we do to solve the problem. One is to stop sewing periodically, remove the thread completely from the machine, slide our fingers down the thread to spin out the curls, and re-thread the machine back up again. The second thing is when a twist is visible in the thread coming to the first thread guide, simply invert the cone on the thread stand and it will unwind itself. You may need to put something on the top of the center pin of your thread stand to keep the cone standing up straight and the thread feeding off freely. We’ve been able to keep our cone standing on its small end, but you could use something as simple as a small disk of hard paper cut with a diameter slightly smaller than the cone, poke a slot in the middle of it with scissors or a knife, and slide the disk onto the center pin of the stand.
CD in Oklahoma