David wrote...

Size?

Assuming this is a similar model (SX-PX 20) then;
the service manual downloadable from...
http://elektrotanya.com/technics_sx-.../download.html
doesn't say much only...

Speaker 1 = 16cm 8ohm
Speaker 2 = 12cm 8 ohm
Speaker 3 = Horn tweeter 16ohm.

It does mention that there are Stereo Left and Right audio outputs on
RCA on the rear panel which if present on your model could possibly be
used if no luck with the speaker(s).


To download the SM you should click the small red left and right arrows
to the right of the cover image to view several ads, a "Get manual" link
will eventually show and it will then download.


--
Ken O'Meara
http://www.btinternet.com/~unsteadyken/