Magnavox TV model RS4254WA02, Ch. 19C506 no audio

This set has no audio. I cannot get external audio in or out either.
There is also no SAP or stereo LEDS display when its on. I probed for
audio on the stereo amplifier board and found none. The audio
processing seems to be done on another large standup board off the
main board. This set is difficult to work on with no schematic for
this reason. But the customer really likes the set and wants me to
save it if I can. Is anyone familiar with this set or does anyone have
a schematic for this model who might be able to look at the audio path
and see if they could assist me with a troubleshooting procedure? Or
is there a noted audio failire on this model? Thanks very much for any
assistance.
Lenny Stein, Barlen Electronics.