Yep, unfortunately, parts for older sickle mowers are getting hard to find because the only companies allowed to manufacture them are those who were in the business of doing so prior to the enactment of certain safety regulations. Jari is one of those companies. They do invite owners of older, no longer available machines to contact them, because they supposedly still carry some parts. Don't know if they'd have what you're needing, but it's at least worth a try.
http://www.jariusa.com/universal_sickle_parts.html
http://www.jariusa.com/universal_sickle_parts.html