TurboDuo audio issue

[ApolloBoy]

I recently got sent a TurboDuo to recap, and while I've now completely recapped the console, I'm having a strange problem with the audio. The HuCard and PCM audio work great, but the CD audio is quiet and the headphone volume knob doesn't do anything, it just outputs line level audio. I've done some continuity checks to the associated vias and traces and everything checks out. Is there a possibility that one or more of the op-amps are shot?

[BlueBMW]

Check the power supply pin to each op amp.  There are some vias that like to get corroded and cause a loss of power to one or more op amp.

[ApolloBoy]

Got it fixed at long last, it turned out that pin 4 of IC506 was severely corroded, so I scraped off the corrosion and reflowed the solder on that pin. Sure enough it works great now!