[Reece]

Great! You got it going. The other transformer you mention is probably the other interstage audio transformer. You'll have one between the detector and first audio, and then another between first audio and output. One of these is the one you found open.

To figure out that capacitor, which I guess IS a capacitor, you could try clipping in some different ones. In those sets the caps tended to be large sometimes. I'd start with an .001, then an .01, then a 0.1 and see what happens. If it keeps getting stronger try a 1.0. On second thought is this in the grid leak circuit? If so the classic value is .00025 mfd which is 250pf. You could use a mica or ceramic cap close to this value if indeed this is connected to the grid of the detector. Although with it out of circuit and the radio working, it must not be?

If you know which of your '01A tubes had the strongest emission when tested, you could try that as the output tube.

There is something else you could try. The 01A tube as an amplifier would like some negative grid bias which some sets provide with connections for a C battery. You didn't mention any such connections on this set. The audio output tube on your set has its grid returned to ground, either through a transformer or through the work around you installed (wasn't clear which of the two audio transformers was open.) In any case you can connect a C battery to the output tube. Lift the grid's ground return. Connect a 4.5 volt battery with the + side to ground and the - side going back through the transformer (or work around) towards the grid. This will give a negative grid bias which will reduce distortion and help volume.

For the 4.5 volt C battery you can use three AAA or AA cells in series. You could use a holder from Radio Shack for them or just quickly solder them in series and tape them in a bundle as they will last shelf life; they are not called upon to provide any current.

The '01A tube can handle up to 135 volts B+ but I'd get the grid bias C battery going before trying anything over 90 volts on the output tube. Once the C is going, see how the volume is. Then you could try 100 volts, maybe 120. You are not going to get ear-splitting volume out of an '01A no matter what. It would take a different type of tube in the output section for that.