[78-L] fake stereo

[Christopher Steward]

This is not quite on topic, but I'm sure there are plenty of people who can give some information/advice. 
   I'm interested in restoring an 'electronic stereo' disc to decent mono sound; clearly I need to reverse whatever original processing was applied, if possible, but I don't know what that would have been. Were there different approaches? Can anyone advise how I can go about investigating this?
Thanks,
Chris