Try Newton or Newton Knits in California. Google to find it. They were the US distributor for Toyota machines before they were discontinued. At one time they had supplies of parts.
I have a complete model K-747 system and all the attachments. The ribber, lace carriage, extra carriage, and many extras including some cone knitting yarn. I am looking for a good home for this system. It was left to me by my grandma and is in excellent condition. Please respond if interested and I can go into more detail.