I came across this link to a Popular Science Reference Library # 15,
Common Repairs for Electric Trains. I believe that it's from
the 1950's, but anyone running Post War or pre war Lionel, American
Flyer & Marx Trains will find it interesting & helpful.
http://www.slsprr.net/technical/PopSci%20RefLibr%20No.15.pdfEnjoy!
Dave