[Arran]

 I believe that the dial is the same as a 38-116, which would make sense since the RF sub chassis is the same apparently depending on which code number of 38-116 RF deck matches up with the 38-690. I think that the main difference between a 38-690 and a 38-116 is in the audio amp and power supply stuff, which is a good place to begin the electrical restoration I think.
Regards
Arran