CM3 - Speaker - No audio out of one channel

[JoeDat]

So, I've recently noticed that I'm not hearing audio out of one of the channels from the speaker.  It was hard to catch until I started playing games with stereo audio.  I don't have the problem when listening through headphones.  I think it's the right channel.  I've tried reseating the speaker cable and also reversing the plug.  Not sure how I can tell if the problem is with the speaker itself or the leads on the board.  Solder looks good.  Any ideas?  I was looking for a way to change the L/R balance to see if what sounds like no sound might be either faint or static, but not sure if this is possible.