Vintage transistor tester manual

I recently acquired a Future Electronics FTC-401 transistor checker. It was made in Japan.
i cant find a manual for it anywhere. There is a new company listed with the name “future Electronics “ but they know nothing of it.
I have attached a photo. Anyone know anything about these units or perhaps have a manual?
thank you!

Ico is defined here: https://www.idc-online.com/technical_references/pdfs/electronic_engineering/Transistor_Currents.pdf