Originally Posted by
Pennyhal
If it does ok on the blue, but only has problems with the brown, I doubt it would be a machine problem. I notice in your photos that the problem seems to occur at the intersections of four fabrics. Also, the bobbin thread isn't catching. I'd try changing the needle. A sharper needle might be able to go through all those layers easier and catch the bobbin thread.
I changed the needle, and it seemed to help slightly. I played with the tension, and putting it up very high seemed to make it work (although it's pulling the bobbin thread, which is a different color, up to the top more, but I think I can live with that if I can just not have those thread breakages and loops).