[simpsons]

Frank

The photo you show of the speakers clearly shows that the connections are soldered. In addition, the speakers are designed with few opportunities for the ingress of material even if loose foam chips have been used rather than foam sheets.

An earlier post said all was fine and so the new fault, playing the unit at high volume could be vibrations to the radio,amplifier from the speakers or just the speakers not happy.

Replacing the speakers with just "better" versions is unlikely to show much improvement if only because of the design which was for an am only radiogram and if it sounds great to your ears, leave well alone.

Chris