Well, I have failed miserably already. As it was all sealed up and in my attempts to remove a speaker from outside the box I managed to pull its spade connection wires off I now have no picture of the polarity of the connection of either speaker.
As its an analogue signal it will be polarity sensitive (the old speaker-cones going in & out in unison). As I have no record of how it was there is a 50:50 chance of getting one pushing while the other is pulling
No wiring diagram( with colour codes) exists so this could be problematic. I just hope there is enough slack on the input wiring to allow me to plumb it in to get the radio or cassette driving it without fully rebuilding the box.
At least then I can try a polarity reversal and play "Better/Worse" like the opticians do.