I found an old roundy socket today in a parts box I bought from someone.
Here are pictures.
It is dirty and I don't know if it is good, but all the wires are there and seem to be solidly attached.
5$ plus shipping and it's yours.
PM me if interested.
You could also attempt to take out the rivets that hold the two bakelite halfs together on your socket to get to and rersolder the connection of the wire and terminal for the focus pin. I once fixed a roundy socket that I had riped a wire out of in this manner and it works well.