It has a lot of great material on some of the more obscure aspects of what I'd call "typewriter tuning." Also covers many brands of standard machine, including; Underwood, L.C. Smith, Remington, Woodstock.
There is an online version available here: http://www.maritime.org/doc/typewriter/index.htm
This manual is printed single-sided, which was a little off-putting at first, but then I realized that it will be great for note taking.
I do not know where my wife found it, nor how much it cost, but I am sure that an inquisitive soul will be able to locate it just like she did.
Best of luck, and Happy Typing!