Ok, great!
First, I added the Channel Mixer layer:
Red 0, 0, +100, +8
Green 0, 0, +100, 0
Blue 0, 0, +100, -5
Masked on gently to the area. That'll do most of the work.
But then I decided that some areas were still a bit too light, so I added a dodge and burn layer below the Channel Mixer layer, and burned a little.
Please don't wait too long to take the Channel Mixer Class. It's so handy for all kinds of issues.