Known issue where the instruments soft lock progress.

Quit out of game. Go to save files, 'save0', scroll to bottom and add 

"s objectXX instrumentY:1"

X: is your next object number (Ex: 10)

Y: the next instrument number (Ex: 3)

thanks a ton dude! since this game isn't gonna update, this seems like the only possible solution. Also, if anyone got stuck on the first instrument like I did, keep in mind its ID is 0 and not 1

Worked for me, thanks a bunch!