Thanks for your input, guys.
Rich:
Time? what's that?
If it were a later set, then I would not bother with all this, I would just replace the components.
As someone who is also involved in restoring old clocks, I have this thought about us regretting the way we restored a 1930s set in the future. To give an example, a 17c clock may have had new parts made from modern brass fifty years ago, but we would now be replacing them with 70/30 brass which is now made for this job. Not with any intention to deceive - we always put some documentation inside the item, or even mark the replaced parts.
Paul:
I hear what you are saying about choice of material and this was probably the main reason for the question in the first place.
I am fairly sure that there is something I can use with reasonable thermal and insulating properties to coat a resistor with, and AFAIK most epoxy resin compounds would be fine for withstanding 400v or so across a silver-mica capacitor potted in it. After all, many electronic ignition modules are potted in epoxy, and a typical coil primary pulse is 400-500v. I also know that triplers have been successfully repaired with this stuff - I won't tell you how I know
David:
The problem with my resistors is that quite a few of them are missing, due to a 'rebuild' done about 55 years ago. I will be doing the waxies and electrolytics in the time-honoured way.
Dunno about your valve rebuild, but I
have made a few solid-state PL802s when they were in short supply!!
I would welcome any further comments, with the risk of being branded an anorak!