Update: BOTH brake lights now work. Hmm. Hopefully not a dreaded intermittent problem. The only variable is that I have removed the CHMSL to replace a few burned out bulbs. Let's see what happens when I return it to its spot. Everything else is working as it should - front and rear signals, flashers, tail lights, and I can clearly hear the flasher clicks. Once the CHMSL is back in place I will post a follow up.