Thanks for posting this thread. I just took my Bernina in for servicing. It was freezing up on me. The tech changed a part, I picked it up then it was giving me issues with tension. I took it back in today and the tech told me I needed to use Mettler. He said Gutermann is not as good, but never to use Coats and Clarke. I guess I need to get rid of all my threads that are not as good...sigh...it used to take any thread before it started freezing.