Huh... you're supposed to clean the board before using it?  I did not know this.  What's the standard method?  Flux and then alcohol?

I recently decided to build a CMOY amp, with directions from Tangent.  I assembled it to the point where I can test using the alligator clips as suggested in the tutorial and am having trouble figuring out what's wrong.  When I hook it up sound plays through the left channel of my headphones and...