Can't view or edit waveforms in timeline

I am pretty new to FCPX. But I know I did this particular thing last week. I want to fade out a song at the end of my movie. But the waveform for the song is not being useful or editable. It is a very narrow (vertically green stripe in my timeline. There is a barely recognizable dark gray line across the song in the timeline, but I can't find any way to expand this to make the actual waveform visible so I can put handles on it and do the fade. I can't find any commands for making the waveform visible.

I have searched the help thing within FCPX, and I have searched the Apple book about FCPX, and I have searched the internet. On the net, there are some references to problems like this from several years ago, including a command + option + W command, that doesn't work, so it must be an old key combo.

I haver restarted Final Cut, I have rebooted my computer. Nothing is helping me. What's the scoop, folks? Am I missing something really obvious? Thanks for your help.