I know there's a term for this, but it escapes me.  I'm editing a podcast and I want to insert a quote from an old speech.  The audio is not very good - but that's ok because it's a historical speech.
 
When I sum it to Mono - the volume drops almost completely.  Zooming in, I can see that the two waves are exactly opposite...  Therefore they cancel out.  
 
Is there any way to correct this?  I would be fine splitting the audio and just having one channel. 
I've tried using Channel Tools plug-in, but can't seem to do it.  Any help is appreciated.

I am in 8.5.3 so I don't know if this is applicable but ...
 
When you inserted the channel tool into the stereo track did you invert the polarity on only one of the two channels?  With the tool you should be able to invert the polarity of the L and R channels individually. 
 
If that is what you did and it didn't work and the L and R channels exactly cancel each other ... then most likely the two channels were simply polarity inverts of each other originally (maybe a remnant of some sort of attempt at M/S process ... but I speculate) and the simplest solution would be to use only one.  Just export (or bounce) the track as two mono tracks.

Yeah - I think you are right.  I'd like to bounce the tracks as two separate mono tracks - do you know how to do that?  The only options I can see are to "convert to mono" and that just gives me a silent track...

Ahhh... Found it in the export menu.  Thanks.