Yes, I've changed everything multiple times. Both machines have FMQ with any thread previously - even rayon embroidery thread. Both machines' tensions have been set as low as they can go just to sew a decent seam, so I think it's time for a new tension spring. I found a shop that will work on them in a town 50 miles away. I may one in for an estimate tomorrow as I have a PT app't there. I'm kind of committed to this thread for this quilt - it's probably 20% done in it, so switching might be a problem. I could switch just the bobbin.