Wow, this should be very easy to fix then.

I bet you could troubleshoot the resistor by simply shorting across it for a moment while playing sound. I can't imagine that would really hurt anything.

As always, be careful not to touch anything on the analog board while the Mac is on. There are life-threatening charges on there. For extra safety, always keep one hand in your back pocket and work with the other. This reduces current across your heart if you are to get shocked which can save your life.