Chart Rectification teaching tools using EA principles

[FreshlySpirited]

Hi all venerable EA gurus! 

I want to learn how to do manual chart correction, and am willing to put in the time and the work.

I am aware that I can purchase software like Sirius and Jigzaw, which will do it for me--but this will not teach me the workings of it. Also--I have not yet read enough of JWG's books to know if he addresses chart rectification, except for the Pluto list of questions. I'm currently about a third through the Pluto book, and halfway through Structure of the Soul.

So with that--can the kind folks here recommend some stellar books that will teach me how to do it?

If there is a JWG book on it I'd love that title, as this is the book I would purchase first. And if not, I would prefer a book by an evolutionary astrologer; as I prefer it to other forms of astrology.

Inexpensive courses / classes are also of interest.

I am unfortunately currently precluded from studying with an astrologer, my budget limits me to reading books / watching videos and podcasts right now.

Thank you so much for any advice you can give me here.

Bless you all.