Is the sound amp working? Does it produce feedback when you touch the pins? If you jack the volume pot all the way up, does it produce feedback?
If there is feedback when you touch the pins or increase volume, the amp is doing its job, otherwise replace it.
If the amp has feedback but no audio comes through, check the op amps for signal coming in and going out (use micro grabbers wired to a pair of cheap headphones).
Roms 18 and 19 are OKI samples, rom 9 is Z80 data for the audio.
Likely your fault is not the caps or roms, but the op amps or amp itself.