[Arran]

Mike;
  I looked at the schematic for that set, what an odd duck. Why would they use two filter chokes, and a field coil speaker, it almost defeats the economic advantage in building an AC/DC set over an AC one? I have a Kadette radio from the same era, 1936, and the only choke is in the field coil speaker. James Skinner must have been taking time off when this design was approved. 
  By the way, I think that the two shaft bushings may have been a phenolic material, possibly to isolate the control shafts from the chassis, otherwise they likely would have pressed a brass bushing in each hole, and called it done.
Regards
Arran