My machine is only 8 mths old and I hoover it out at least once a week or before I change from embroidery/piecing to quilting and vice versa. I had pieced about three quarters of the king top before it started playing up. It worked great with other thread but as I said whenever I snuck the bottom line in it 'put down tools'. I also tried it with a 70, an 80 and a 90 needle - all fresh out of the box. Perhaps it is just this cone of thread that's dodgy? I've used bottom line loads and loads of times, I've even used it to quilt with. I love the fact it doesn't create the same build up of fluff as cottons do. Anyway I'm about to begin quilting this top and bought some mettler silk finish to see how it goes. I read on one thread that a few ladies liked it.