The handlebar assembly of my 1931 A31 is integral with the top clip or yoke, and I imagine is similar to other models of this era. As shown in the attached image, there are two square-section cutaways in the lower edge of the bore which fits over the steering stem - one on each side. Can anyone advise what these are for? I am guessing some form of locking washer, with dogs which engage in the cutaways and edges which fold over the faces of the bearing nut beneath. This is just a guess, though and it would be helpful to know the correct answer before I complete the reassembly. All comments appreciated.

[Attachments converted to linked images. 25Nov21 -Doug]