[Premium-Rx] Help: ID shaft encoder

[Tom B]

Hello All,

I am working on a Racal RA6831 receiver.  There is a problem with the 
shaft encoder.  I would like to find a replacement but there are no 
markings on it except what I think is a date code (8922) and the number 
64 on the connector.   It is small, about one inch in diameter made out 
of black plastic with a four pin header.  I can send a photo if needed. 
Could someone tell me who made this thing?

Tom Bryan
N3AJA