[RodB]

I think your tuning shaft has lost a C clip that holds it together. The inside shaft is separated from the outside shaft with 3 or more ball bearings setting up a planetary shaft where the inside shaft rotates at a ratio to the outside. The inside shaft may also be serrated to keep the whole mechanism from drifting. It all needs a good cleaning and lubricating. Don't loose the balls. My version is from 1935-36 and has a spring loaded friction disc at the business end that moves a thin curved rod attached to the dial. I believe yours has a gear attached.