Chuck Harrington's nifty website myflyertrains has repair manuals for almost all Flyer stuff, including transformers. here's a link to the 30B wiring diagram:
http://myflyertrains.org/gallery/album211/18B_30B_2
As I suspect you know (but just in case) most older transformers should have their AC powercord replaced - since you are digging around inside, its a good time to do it. You can find 'replacement' cords on eBay or, since they aren't anything special, the local hardware store will likely have 2-prong cords (or three if you want to add the ground). If you do get a a cord that can only be plugged in one way (fatter prong on the neutral side), then pay attention to the wiring diagram so you can get the wiring 'standardized' should you add another transformer. This is to ensure you get them phased correctly.
