[Arran]

You have it backwards, the 6E5 was the original Magic Eye tube introduced by RCA in 1935, the 6U5/6G5 came later, the 6E5 is more sensitive to changes in grid voltage so that was why they came out with the later types. That doesn't mean that someone didn't add the eye tube, I've seen them added even on early 30s sets sometimes. As for the filter capacitors it may have been that the positives were connected together and the speaker field coil was connected in the negative leg of the power supply, such as between the transformer center tap, and the chassis, with some bias resistors in series with it. I doubt whether you will need a replacement power transformer, most of the time they can be made to work unless the transformers are completely wrong like the transformer is too small to handle the load, or is putting out 2.5 volts for the filaments when you need 6.3. The old output transformer can be replaced with a generic single ended unit, you don't need a universal one, one of at least 5 watts should be sufficient. Like this one here: https://www.tubesandmore.com/products/tr...ngle-ended
In terms of faults I would check those old dogbone resistors, that may account for the weak performance, as would a wiring error from not having a schematic to go by. I will see if I can find a schematic for this thing, I would pin the age at about 1936-37 or so, that model number sounds like a serial number so I will search by chassis layout and tube lineup,
Regards
Arran