Well, I bought a Brothers NX-250 which I do not consider inexpensive. I too have had that problem. I have found that both times the looping on the back has happened, I had to take everything apart and there was something down inside that was making it act up. I love this machine and it sews nicely. This machine is two years old but I haven't used it very much and still trying to get used to it. Both times it acted up, I rethreaded, new needle, all the usual things. Nothing worked. Then when I took it apart I found either a piece of material or a piece of a pin somplace around the bobbin case. Once that was cleared out it worked fine.