I have a Franklin 117 from the 1930's that is the same as the White 77. I think this machine has the same head as the Whites from the 1920's. I found that there is a device sold on the internet as a "daring attachment" or a "darning spring". Some are sold under the Domestic brand name. It is a tapered spring that fits around the needle and is held by the needle set screw. I basically acts like one of the free-motion hopping feet. Remember, the feed dogs do not drop on most machines made by White, so I made a feed dog cover out of a 3" by 3" piece of plastic and taped it down. I have never found a walking foot for the machines of this type. The Singer walking feet will not work because the distance between the presser foot shaft and the needle shaft is wider on a White than on a Singer. The exact width of the feed dogs is also not the same.