[R-390] R-392 Mech.Parts Question

[Harry Joel]

Hello All 

checking out my recently obtained R-392, I discovered
the Bandwidth (three position) knob was free-wheeling.
The coupling from knob shaft to rotary switch shaft is
made up from three pieces. There is a matching slot on
the top and middle coupling piece.  A part must have been
there at one time to link the two together. A view is here:

http://www.cyberlane.net/~organic/R-392-Bandwidth-Coupling.jpg

I dont quite understand the need for a three-piece coupling here
and would like to hear from experts.


Any help from R-392 owners is appreciated. I am still in the midst
of resolving the DOA condition of a receiver that, according to the
seller was last used some years ago and worked fine. Shoudda 
spend the time to take the Greyhound to the owners city to assess
the condition of this receiver. Mechanically it seems to be in
better than average shape. The tag says Serial Number 698 -
Reworked by Stewart Warner Electronics. Inside markings tell me
that it was built by Collins.

Harry