Thanks for the pictures. Too bad about the case. You might be able to force some wood glue into the break and clamp things back together. After the glue is dry, sand lightly to smooth the edges out and coat with some shellac. The repair will show but the case will be usable.
I don't think any of my Whites have that knob. I think it's the clutch knob for bobbin winding. Mine have a little lever you flip in and out to work the clutch.
Does anyone know if White made hand crank versions of their machines? I'd like to see one.
The two holes in the back of your pillar are where a Hamilton Beach motor on a swing away mount was attached.
Overall your machine looks complete and it's in good cosmetic shape. I think you did really well. White Rotaries are really well built machines.
Rodney