I'm often asked for a source for sewing machine manuals. To get a manual, you will need to know your machine's model number. If you're not sure of the model number, Sewusa has some pics of machines to help identify your model number. Another source is SewingManuals.com.
If you are unable to find your machine's manual at either site, another option is to go directly to the manufacturers site. About.com has links to each manufacturers website.