[Mondial]

I don't think a regular output transformer will work in that radio. It has a high impedance magnetic vane speaker. What was the resistance of the speaker coil you rewound? 

Replacement audio output transformers typically match impedance of the plate circuit of several thousand ohms to the few ohms of  the dynamic speaker voice coil. Unless you rewind the speaker coil with only a few turns of heavy wire, the speaker will not present the optimum load to the plate circuit and you will get very low volume.

You might be better off using a high inductance choke to feed DC to the output plate and capacitively couple the speaker to it. This was standard practice with the radios of the period, such as the AK 40, Radiola 60 etc.

http://www.nostalgiaair.org/pagesbymodel...040337.pdf

http://www.nostalgiaair.org/pagesbymodel...001354.pdf