Welcome to the world of digital electronics! Unless you get lucky, you're going to have to learn some things. As for the guides such as Clays, they are the bibles to the basics of pinball repair. They are specialized to pinball, and assume you know some basic electronics.
There are some basic electronics courses you can take, or search online. The first things you are going to need to learn are A.C. and D.C. measurements, how to use a multimeter, and how to test continuity and resistance. Until you get these basics under your belt, resist the urge to open your machine.