Chapter 4After spending some time in the mountains you will reach a big house that belongs to an inventor. Spend some time looking around and walk up a staircase leading to a machine with a lot of pipes. You need to interact with it until it plays the right tone, making the inventor dance of joy.
Put the little brother on the rotating lever and the big brother on the horn-thingy that you can push. While rotating with the little brother move the horn to the 5th hole (counting from the left), and you should play some sweet tunes.
Image of machine:
https://steamuserimages-a.akamaihd.net/ugc/74000830345163295...Solution sourced from:
https://steamcommunity.com/sharedfiles/filedetails/?id=17598...