[morzh]

Radiola Dave on Facebook confirmed his 84 also has a similar problem. Not very strong (nor is mine) but noticeable when the radio is not playing.

Oh...forgot to say, I think there is no humbucker in the speaker, but just in case there was, I plugged the speaker plug from inside the chassis. This reverses the field coil. While the humbucker, if it was there (which I think it isn't) would not change the direction, so some change would be noticed.
Well, as expected, no change whatsoever.

So, tomorrow I will put it back together one last time, to be taken apart only in case of something going bad and in need of repair.