looking for an old IBM knob from a 609 calculator panel

[Bob Rosenbloom via cctalk]

A long shot I know, but I'm looking for an IBM knob that's missing from 
a 609 calculator panel I have.
Photos can be seen here:

http://dvq.com/ibm/ibm-609-pnl1.JPG
http://dvq.com/ibm/ibm-609-pnl4.JPG
http://dvq.com/ibm/ibm-609-pnl5.JPG
I have no idea if the knob was made by IBM or was a common knob of the 
times.

Thanks,

Bob

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Vintage computers and electronics
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