Guacamelee Cheats: Where to find the Mariachi Band missing member guide
One of the quests in Santa Luchita is to find the missing member of a Mariachi band.
The location of the missing Mariachi band member is in a red building in Santa Luchita, located all the way at the bottom and to the left. The locations is shown in the picture below:
After entering the building, you will see blue blocks on your right. To get through those, you will need the Dash Punch power -- only that power can get through the blue blocks -- and it is performed by pressing Left or Right with the Circle button. Once you get through the blue blocks, you'll see the last member.
If you don't have the ability to smash through blue blocks, continue playing the game and following the story missions until you get it.