Unbranded machine tone-arm question

[rw101]

I’ve dismantled it now, and can see how it should fit together so there is no vertical movement. You can see down into the tone arm, there is a small plate has been welded on, and the pointed end of the shaft sits in that, with the brass nut in such a position that it comes through the hole in the middle once the two pieces are connected. The other nut then goes on to keep it all in place. I cannot tighten that too much though otherwise it will impede the lateral movement of the arm. Do you think it would be an idea to employ a second, locking nut that allows the lateral movement but stops it coming loose again? I think there would be room.
I think the cracks that you noticed area trick of the light in my earlier photo. They are shadows rat hare than a crack. As to how much is pot metal - how do I tell?

[JerryVan]

I'm guessing the small brass piece is threaded to screw onto the post, like a nut? How well does the outside diameter of the brass piece fit in the cross bar of the tone arm? Fairly close? Sloppy?

[rw101]

Yes that’s right, the brass piece is threaded and one end of it is flat-sided so in theory you could hold with a spanner. The other end of it is circular and fits closely inside the circular hole in the cross bar of the tone arm. I shall have a play around, as it’s obviously been designed to fit tightly but to allow lateral movement of the arm (as long as there’s nothing missing).
If I only had a needle screw for the soundbox I’d be able to test it all out!