[Arran]

I wonder how they lost the knobs? I know the kind, then have half shafts, and the half portion is about 3/4'' deep, and they have a steel spring inside, so it's not like there isn't anything to grip them onto the shafts. I haven't moved in some time time but I can't recall the movers loosing a knob on a console, in fact they wrapped the cabinets in moving blankets and then wrapped tape around them to hold them in place, so it just wasn't possible for that to happen. If they are missing I have a feeling that someone swiped them at some point along the way, unless the chassis was just sitting inside  bouncing around rather then being bolted down. The good news is that these 1940s style RCA knobs are fairly common, especially the smaller size ones, they were used all through the 1940s on everything from radio phono combos to AC/DC sets, I've seen them in bulk lots of knobs on fleabay, as well as being listed as RCA knobs, avoid the radio butcher Polecat on there unless you want to pay $20 a knob (or just on principle), keep your eyes open for broken RCA Bakelite sets that still have the knobs, those can turn up anywhere.
  The service info David posted came out of Beitmans, which shows that they were a fairly popular set when they were new, it's nice that they have dial cord diagrams but they don't seem to give the length of the cord you need. Dial cords can be tricky if you aren't used to dealing with them, once or twice I have have found that the cord doesn't travel correctly when following the factory service info and had to improvise slightly. I have also found that if you can't get actual dial cord that braided fly line backing for fly fishing works as a good substitute, though it is stretch so you may have to shorten it to get the right tension, 15 lb test or higher is best.
Regards
Arran