As I mentioned before, I have no experience with machines of that age. I like Singers from the 40's and 50's, because it's not hard to get parts. I've heard of
Helen Howes in the UK for vintage parts. I usually rely on Ebay, but I'm not sure it will help. I did a search for "Davis Underfeed Parts" and came up with this
post. They are helpful people who like REALLY old sewing machines. They may be able to help you.
bkay