Glenn,
is your power supply ok?
If the supply voltage drops below 10V, the audio output stage will not work.
You will then only hear sound through the headphone output.
When I used the battery in the initial period, I once did so that the battery was very low and the sound was muted.
So this audio amplifier IC is the best low voltage monitor.
Then I was also thinking about replacing the IC!
--
Gyula HA3HZ
HA3HZ