Them and Pre-Owned Electronics (?) offered complete kits of the parts that Pina recommended replacing/upgrading.
Pre-Owned sold the kit (no book though) for $50 each, but, if one purchased 5 or more, the price was $25 each. So if you were going to get 3 you might as well get 5. I bought five, once.
Given the disappearance of all sources of flyback transformers, I wish I had bought more, but I didn't have very much money back then (like add up your grocery cart to make sure it doesn't overdraw the bank account).