So, you'd prefer strong treble and poor bass?
This radio has an electrostatic tweeter with a foam insulation between its electrodes. This insulation tends to decompose over time and the tweeter is most probably dead, so that might explain part of the loss in the treble register. But usually the remaining main speaker produces enough treble.
Next, the tone control circuits in these radios work with R/C combinations, with one of the resistances being a potentiometer. The condensers used in those old radios become leaky over time, so it might be a good idea to replace them by modern equivalents.
Ralf