SmithCorona.com offers the PDF versions of Smith Corona manuals for free, as of December 2015. The website has the official manuals for various types and models of Smith Corona typewriters.
From the SmithCorona website main page, scroll down to the footer, then click on Typewriter Manuals. Click on the link for the appropriate typewriter model. The manual either appears on the browser window or loads into the designated downloads folder.
To open a downloaded manual, navigate to the downloads folder, and then open the PDF file that has a file name that is related to the model name of the typewriter.