Sounds like either an impedance mismatch or a phasing issue. The ceramic cartridge requires very high input impedance and that is normally deigned in to the amplifier, but if the amp was deigned for a magnetic cartridge, you’d get these symptoms. But that’s unlikely since most record players in the 50s were ceramic.
So it may be phasing. You can check by only using one of the two cartridge channels, leaving the other one disconnected. If that sounds OK, connect the other one in parallel (not series) and if the sound dies reverse the connections in that second channel. Remember also that one of the connections to the cartridge has bias volts on it and that has to go to the correct pin in each channel.