adventure through inner space

I'm stuck on part 6 - Make people dance by playing your favorite tune. I don't know how to play music because I don't see any mixer at the monorail. Is there something I'm missing or is the monorail incomplete?

Happy Space Month! I'm trying to compete the Adventure through Inner Space Quest so get my spacesuit and I'm unable to do so because the music game seems to not be working. Please let me know what I should do, I really want to complete the quest!