How to Recover MIDI files from Garageband projects

The crux of my question is this: Where and how does GarageBand save MIDI files? My project file is in some way corrupted and I want to recover my MIDI tracks. They were saved before the file was corrupted, so I know that they are in there somewhere. My best guess is in the ProjectData, but I have no idea how to interpret that file.
The full situation: I saved my project, but Garageband glitched and all of my recordings and MIDI tracks went blank. Upon trying to reopen the file, I got a message that said "Illegal Sequence" and gave me options to 'Repair' or 'Quit' (see picture below). 'Repair' opened up an entirely blank Garageband file, and 'Quit' just quits Garageband. By control-clicking and selecting 'Show Package Contents' I was able to find the Audio files I had recorded. However, the MIDI files are nowhere to be found. Is there any way to recover the MIDI files? Or figure out what part of the project file is corrupted?

I'm using Garageband Version 6.0.5 (428.5) on a 13-inch late 2011 MacBook Pro running OS X 10.9.5

Thanks!