4-Cart game with very weak sound

I have a dedicated arcade game that has very weak sound. The sound stays at the same level regardless of the poteniometer position. All of the voltages are good on the HA13001 IC. All of the sounds are there, just very low volume. Any thoughts other than the amp IC.

Where is the stereo sound being pulled from on the 4 slot board? Is it coming from the JAMMA harness? Or is it comming from the 4 pin connector near the two headphone plugs?

Something audio-wise is bad on my 4 slot board so that the headphone jacks don't work and only one of the channels produces appreciable audio from the 4 pin connector. The other channel is really quiet.

However since the stereo audio pulled off the JAMMA harness works just fine.

The sound is wired through the JAMMA harness. I get the same situation from the 4-pin. I have further noticed that the left channel will go quiet as you turn the volume down whereas the pot has no apparent effect on the right channel. I have not checked the headphone jacks yet as I do not have anything that is compatible with the jack on the board.