Wow they are some interesting black paper capacitors

Fred the speaker coil is open circuit I have decided that it's off to the speaker hospital with it as it's a strange size coil . The speaker tranny will be replaced with a Jaycar 100 volt line transformer and hidden inside the original casing. I have recapped it now but it's off to my mates place tonight for a little fault finding. This unit has been gotten at but I have managed to tidy it up quite a bit. Those two terminals that are linked at the back are sus as one is wired up but the other goes nowhere. There is a issue with the way the other field coil in the way it's wired up so I will check that out as well

Question This R52 has 3 Potts plus the tuning control. There is no on/off switch , ok so why three Potts? This only broadcast as well.
Edit I believe one pott is a gain control.

AM/Gram switch? It'd explain the coloured binding posts on the back too.

The 52/163 chassis schematic shows a two-position sensitivity switch and a switch to cut the voltage of the dial lamps.

It looks like an antiquated potentiometer in the photo, connected to something in the front end.

The green post at the back doesn't seem to be connected to anything, although looks like it once was.

My guess is that this radio has been got at, some time in the remote past.

The fourth knob is a sensitivity pott. It doesn't feel like a two position knob. I got my head around the field coil too.

The terminals at the back are probably for a record player. One will be just grounded and the other looks like its wired up to somewhere in the audio section?
Fred.

The problem is, that the terminals are linked at the back. If green was grounded (which it could well be), then the audio is getting shorted out.

Rob there were lots of sets with a linked pair of terminals at the back for gramo use.
The gramo signal feeds up onto a resistor ladder to attenuate the phono level to match the radio level.
Typically that would be the bottom end of a audio grid resisitor.
Bit hard to see exactely how it is in that set, or if it was original.
The two holes on the center line suggest the original fitting may have been a bakelite strip with screw terminals or just an earth terminal as the marking suggests. The factory circuits should show what it was/is.
Fred.

And then I did what I should have done, looked at the AWA model 52 circuit.
That shows the option of a "PU" access on 2 terminals at the back connected by a C42 .05 μF cap which you can see in the chassis photo. Leaving it linked would provide a "top cut"! roll off.
Best to see what it does on test.
Fred.

Well I'm dropping this one of to the furniture restorer this week and the speaker is off to the speaker hospital in Sydney. Will send photos when done

I will have the speaker back from the speaker hospital in Sydney very soon. The good news is The humbucker coil and field coil are ok. They are rebuilding the voice coil and going to reuse the spider which is in good order so I may just leave the electrics under the chassis alone at this stage because I won't need to rewire to replace the field coil.
Not a cheap job but I believe in paying for their time.

I'll be very interested in seeing pictures of the repaired speaker.
I've successfully repaired a few hifi speakers which needed the foam surrounds replaced but never actually replaced the cone and voice coil.
Just the surround is a fiddly process which requires removing the dust cover and shimming the voice coil to centre it then removing all trace of the old surround without damaging the cone then gluing the new surround into place and finally replacing the dust cap.
What did they charge for the repair if you don't mind me asking.

I will have the speaker back from the speaker hospital in Sydney very soon

They should be added to the NSW Services Directory, methinks: https://www.speakerhospital.com.au/speaker-repairs

Yes GTC they should be added, the fellow is quite knowledgable about vintage radio. This is not a cheap exercise but I believe in paying for their expertise.