Re: ’30 K50 LU large brass nut & spring

[hotrod]

Tighten the cup until it stops (its threads will bottom out on the gear threads). This will compress the heavy spring somewhat. The spring needs to be one-piece. The face of the cup must be flat and not bulged outwards. { You can do a temporary test by threading the cup on the gear without the spring in place just to see how far it goes – it will stop where it should.}
If water gets into the brass cup or cone, it may freeze, destroying the cup by bulging or breaking it.
The hole in the edge of the cup is for tightening the cup with a spanner type wrench with a pin on the end. It needs to be of the correct matching curvature. (I use a large channellock pliers placed in the right direction so it doesn’t slip.)
A used one can be found on these models: K50, K65, K70, K75, K80, KA37
If you braze the old one, you might do so while the cup is screwed onto the gear to prevent distortion.