Welcome to the Quilting Board from Sunny Nevada! That's right! Jump right in with a question. We love questions! And superior threads IS the best site for thread. I use them exclusively: Masterpiece for piecing, King Tut for quilting, and their silk thread for applique. I was using another thread (from Connecting Threads - another great site!) and it did fine as long as I had my Brother Sewing machine. When that machine packed up, I bought a Janome, which I just love but it's fussier about thread. The threads I just mentioned do great with my Janome: no breaking, linting, or loose threads. So it could just be your Juki needing better thread.
You should check the tension too. If your machine does both embroidery as well as a sewing, your bottom tension could be way off. I'm not that familiar with Juki models to know if yours does this. Anyway, bobbin tension for embroidery is MUCH higher than for sewing, so if whomever set the tension gave you tension for embroidery, that could be your problem.
Around here, we are not shy about adjusting the bobbin tension. We'll teach you how if you don't know.
