I have been looking for back clamp feet for my 66-1 also, or the adapter but I can't seem to find it anywhere. mine came with several feet. the main one is very damaged. someone has pulled the fabric so hard that the needle hit and scared the foot many times I used one of the polish stones on it. It's still very rough. Since I have all the other feet I would like to keep this one as is and use the adapter if I could find it. Any suggestions?