Bob, beings it sounds like you enjoy tinkering with this stuff, why not purchase a postwar Lionel service manual. Plenty of copies available on line, both hard book, or CD, and I even seen one fella offer it as a thumb drive. In the book, E units are explained. The theories of operation, schematics, and part by part breakdown. The sooner you know exactly how the system operates, and how to diagnose faults, The easier it’ll be …….A Lionel mechanical E unit is about as simple as simple gets.
Pat