Reddit reviews Hero I Robot, ET-18, TECHNICAL MANUAL (Heathkit Educational Systems)
We found 1 Reddit comments about Hero I Robot, ET-18, TECHNICAL MANUAL (Heathkit Educational Systems). Here are the top ones, ranked by their Reddit score.
You might try poking around here. It looks a bit stale, but you might find someone with a copy.
I expect it will be a pretty hefty document, though.
Edit: Is this the book you're looking for?