I have a Sapphire 850 and have Fmq about 15 or more quilts on it. Right now having problems with thread shredding. Originally bought 50$ spring foot. The bar sat over the needle screw and hammered til it eventually broke. I switched to the embroidery foot on free motion mode and it worked great. Paid over 100.00 to fix thread breaking, still doesn't work right. My feed dogs also had trouble creeping up. Manual says when you go into fmg mode they (feed dogs) will be automatically set. Mine never lowered except manually. When it works, great when not grrrrr. So frustrated.