Barrel of the via? I’m unfamiliar with that terminology – what is that? I did a continuity check from the very bottom to the very top and everything tested good. When the audio is out, twisting the header a bit would usually bring it back so I assume(d) it was just a poor connection somewhere despite the continuity check.

EDIT: Okay, some quick Googling got me understanding this better. As I mentioned, continuity is good, but I still suspect it’s something in this area. I suppose I could remove the connectors and install solder connectors, instead of press fit?

Do you have a specific link? Is it aerosol (that’s what I’m finding)?

Do I just individually put a drop of that in each through hole basically? No cleanup, just let it rest in the hole?