Apologies for the lack of follow-up posts. First that is because the long Christmas holiday is perfect to do some in-depth restoration and I have been busy doing my next television restoration. Second on a more personal level, there was a death and a stroke in the family over Christmas, and that obviously took priority.
Once I'd stripped off most of the components that needed work on them, the next stage unsurprisingly was to slowly restore them. In conjuction with rewiring and repainting the chassis (which could be done in parallel), this took about 1 and a half years.
With so much to choose from, the first thing I did was to restuff all the waxy capacitors, and in parallel derust, and restore the CRT clamp/focus coil adjustment mechanisms
Why do this first? Because this was easier "low-hanging fruit". After about 4 months of ever-more dispiriting stripping down, it was better to start with things where I could make rapid and solid progress, and especially stuff which I could do in the evening after work. Additionally, it also gave me time to research and think about how I was going to approach some of the more difficult parts of the restoration, including time searching for NOS components.
Moving onto waxy capacitor restuffing. This is a necessary if fairly boring task. In my experience no waxy capacitor from the 30s has survived in full working order due to their nature, and are at best leaky and vastly over-capacitance, and are often open-circuit or short-circuited. You may get away with not replacing those waxy capacitors in a 30s radio, but they'll cause numerous problems in a 30s television. I tend to prefer to eliminate those problems from the start by restuffing them before trying to get the set working, and then concentrating on the real faults when you first turn on the television.
Obviously lots of people have their own techniques for waxy capacitor replacement. Some just replace with modern components, some make the modern components less visible by covering them with black sleeving. It all really depends on how important you think preserving the original look is.
Personally in a rare 1930s television I think is it worth going the extra mile, and preserving the exact look. Doing this makes the restoration more difficult, but perhaps more authentic.
This means restuffing the original waxy capacitors. Even there it seems there's many different approaches. In my first restoration of a HMV 904, I slit the waxy capacitors length-ways, removed the contents, replaced with a modern component, and then glued the waxy capacitor back together with hot glue. As long as the slit can be hidden in a non-visible place this works well, the original look is preserved exactly.
For this restoration I tried a different approach. I noticed the capacitors used in the Murphy were significantly more waxy than the waxy capacitors used in the HMV 904, including a layer of wax inside the paper envelope. This led to the idea if could I heat the wax up using a heat-gun, could I then slide the contents of the capacitor out without any slitting of the paper envelope? In fact I discovered I could do just that. But, of course, it removes all the wax from the capacitor paper envelope.
So the process became heat-up the capacitor removing all the exterior wax. Then heat up the paper-envelope allowing the crimp on one end of the capacitor to be folded back, and the contents slid out.
The new modern capacitor(s) is/are then soldered to the original two metal end-points, then the contents put back in the paper envelope. The envelope is then heated to allow the crimp to be re-crimped. Lastly, it is then redipped in hot new beeswax.
This leaves a waxy capacitor which is indistinguishable from how it looked originally.
Photo 1 shows ten waxy capacitors removed from the set. Photo 2 shows an example of the replacement of the original contents with two modern capacitors. Photo 3 shows the 10 restuffed and redipped capacitors.
Initially when it came to heating up the new beeswax for redipping, I hit a number of problems. If the beeswax gets too hot then it has a nasty tendency of self-igniting which isn't very fire safe. But if the wax isn't kept hot then the dipping is poor, the resultant wax coating is too thick and not evenly distributed. I needed to discover a way of keeping it hot enough for a good result, but not become too hot that it caught fire.
Serendipitously I had recently bought a glass teapot and teapot warmer (to keep the tea hot). I discovered if I put three teelights in the warmer then it provided enough heat to keep the beeswax at the right temperature, and not get too hot.
Photo 4 is a photo of the hot beeswax on top of the warmer. The beeswax is in an old tuna tin