For years now, I have been rebuilding these units. Could be one of my favorite pastimes. They are using cross cancelation and a bit of delay to give the stereo image a 3D quality. I know, I know, you and I already have that in our audio system, so why bother? Much the way I would bother with tube buffer or other device as I have in the past. I love audio and experimentation, if it doesn't cost too much. That would be the case here. For $200 you get a unit that has had all the electrolytic capacitors replaced, the RCA jacks replaced, and even the power cord inlet made into something less cumbersome.
 Ask questions, I encourage it.

 Greg

https://ibb.co/B438TMB

 I must add a couple things here. First, yes, that is a new faceplate and is in perfect cosmetic condition. Second, when/if you look at those other  C-9 units for sale out there, please remember it is more than likely that they have had NO service such as the old capacitors changed out. Yes, it matters.