Looking in my 5 slang dictionaries i can't find foobie, it isn't in a dictionary of railway terms, or language of the underworld. Could it be derived from the US cartoon character Smokey Storer. who used the word "Foo" as a substitute word for anything where he couldn't be bothered to find the correct word. the manufacturers might be accused of; couldn't be bothered to find the correct prototype. the word Foo was used by the RAAF and Richard Hendricksen was a keen and knowledgeable aviator.
Why is there a resistance to FUBAR as the origin? One can readily describe a lame model with the words behind that acronym (whichever word starting with "F" you prefer). It has always seemed to me that "foobie" is a natural descendant.