An optical illusion then.
I'm not sure I have anything else to offer. The signal tracing seemed to indicated that audio is making it through your Reduction, albeit with some channel imbalance, but your audio tests indicate just hum and no audio. While we can do a flat rate repair for you, it seems equally likely that either your Reduction will work OK here or this will just be a matter of solder joints.
Let us know how you would like to proceed.
-PB