At the Stage, in the hallway you can get to after breaking the wall down. There are stairs leading to the right at the end of the hall with the endoskeleton.
Hope this helps!
D'oh. Thank you! I totally missed it, stairs were a bit too dark for my eyes to register playing late at night.I said it before but: great game by the way. I've been completely absorbed in it ever since I picked it up a few days ago.
