If it are a VM it would have a model number/date of manufacture ink stamped on the underside of the base plate - even if VM made it for another manufacturer.
Edd posted the schematics for the 700717 chassis's many moons ago. (Links to schematic images no longer working.) If Edd catches this perhaps he can look it up and see if any part numbers are listed for the cartridge. That will help us help you find a cartridge.
Rick