no audio output from SP-606

[npp1993]

I purchased a used Roland SP-606 a few months ago. The unit seemed to be in OK shape, but the FUNC button stopped working soon after I picked it up, so it might not have been in the best condition. I replaced the button, but I have a bigger problem in that the headphone outputs do not produce any audio. I can get a VERY VERY quiet signal from the main outs. Even when I boost the Low and High master gain by 24dB, the unit is just barely audible.

I've gone through the built-in system test, and the only part that failed was the test where you connect the audio outs to the audio ins and look to see two waveforms on the screen (one from the L channel and one from the R channel). I did not see any waveforms (confirming the issue with the audio outs); however the digital audio in and out test did pass.

When I plug in an external audio source to my audio ins, I do see a signal when I am in sampling mode (although I have to change the input to MIC level, even from a line level source. So, the audio in seems to work OK.

It seems to me like the audio jacks are faulty. I've used Deox-IT products on the jacks to try and clean them out, but the audio issue remains. Does it sound like the audio jacks need to be fully replaced? Or does this sound like a different issue with the unit?

Thank you for any advice!