[codefox1]

There should be nothing in parallel with R100B. If you unsolder one end and measure , you will probably find that it is a resistor, and that in fact R100B is open. You can't always tell by the look of a component.

My best guess is this indicates a repair was done. If this is the case I would remove the the R100A/B resistor and the "extra" resistor, and replace it with 2 1000 ohm ten watt sand resistors. You might have to put in a terminal strip to connect things up, but try to dress the resistors right up to the chassis, as they do generate a little heat. Add a fuse while you are at it. One half amp should be around right.

The reason I would use 1000 ohms and not 850 is because the line voltage is a lot higher than it was in 1948, and the battery set tube filaments are very delicate. If you want to ditch the 117Z3 and use a silicon diode, then I'd probably use 1500 ohms. The 117 volt tubes are not that reliable, and not so easy to find. Add a fuse while you are at it. One half amp should be around right.

Good luck