Vintage Synth Repair

Someone has a Moog Source, and they want me to replace the worn 
membrane switch interface with real momentary switches.

I assume this would just require me to decode which combination of 
wires on the ribbon cable bridge with each switch, and wire an array 
according to those specifications.

I've only pulled back the interface to see the ribbon. It almost 
looks like it's double sided.

Does anyone know how many combinations of wires each switch bridges? 
If there are more than 2 or 3, do they make multi throw momentary 
switches?

Is this project even possible? Is there any documentation of these 
combinations anywhere?? That would save a lot of time.

Thanks,
Mike