Dian,
I have the Sapphire 870 Q and it hates Coats & Clark. I sewed perfectly but made a terrible noise which scared me. Thought something was wrong somewhere in the machine. My dealer said that C&C changed companies that wind their thread & a lot of machines can't use it now. They are trying to get another distributor, at least this is the story my dealer said. I do know when I stopped using the C&C thread it sews perfectly & NO noise. So even tho I had several new spools of C&C I'll just save it for mending & doing hand work. About your spring free motion foot, I had one & took it back, but since then I've learned their is a command in the tool section to turn that on, which I hadn't, I think I just turned the free motion command on, which is probably why I had problems. Duh! You do think the spring foot is better than the open toe one? Glad your other problem is fixed.