Even though it's old-hat, I'd like to try modifying the Korg Monotron Delay.
Korg was nice enough to share their schematic, but not the board layout. Also, the board itself isn't labeled.
I need to know what I'm working with, so I used a multimeter, and some educated guesses to draw the following. I labeled the rough sections of the circuit, so that it's a little easier to find what you're looking for. Be warned that it's not perfect, but should be a decent starting point.