Chord organ no longer outputting chord just glitch + error that Chord Organ_0.6 is too large 4 Teensy

[Morg-A-tron]

I bought a used chord organ from Control in Brooklyn (so I didn't solder it) about 11 months ago. It was working fine but overtime has become unstable in its sound outputs. Root seems to function/track properly but the module is no longer outputting chords just what I'd describe as dirty oscillator forms (e.g. sine wave sounds more like a saw with rich harmonics but not a chord). I tried to reinstall the firmware but am getting an error message that 0.6 hex is too large a file so currently operating on 0.5 beta hex 86%. Any suggestions appreciated!