For parts, post a free "Wanted" ad on the classified board here – usually someone will have what you need.
If that doesn’t work, there is an outboard junkyard with motors that date back as far as 1906, and they do mail parts – it’s at:
http://twincityoutboard.com/
You will have to call them at: 952-496-1951, or e-mail them at: tcoutboard@tcoutboard.com because they don’t list inventory online.
Located just south of Minneapolis near the horse track if you live near there, go in person.
Dave