1935S
Since I couldn't find a part, I took a #10 Allen screw(0.187" shank), chucked in in my old Craftsman mini lathe an filed and sanded it down to 0.180", the maximum that would pass through the frame. Since Allen screws are grade 8, I think it will be hard and strong enough for the job. Next, I plan on locating a piece of 4140, preferably pre-heat-treated, and filing out the arm for the slide lock with a hole for the pin. If I can get that working, the next step will be to cut the excess length off the Allen screw and either cut a groove for an E-clip or drill a hole for a spring clip to retain the pin and turn the head down to get rid of the socket. Then the arm can either pivot on the pin or be tack welded to it. I'll report back later, if I can pull it off. Of course, maybe no one really cares, but I'll report anyway.