I'm requesting suggestions for reference material on making a voltage regulator to replace one missing from a 4.5KW Kohler 4.5CM21 generator (it seems the generator was cannibalized before I bought the RV). New regulators are available for about $400, but I'm hoping there is a more reasonably priced alternative in making one myself. I have on backorder from amazon.com a book titled "Generators, Exciters and Voltage Regulators", but I don't know what's in it.