As someone who's sold hundreds of those... You might have the wrong product name, or it changed over the years. I sold them under the name "X-Tract" for about 5 years. Here's the product page:
http://www.buckknives.com/index.cfm?event=product.detail&productID=2930
So they likely have the parts you need.
I got to get a new one my buck broke .check out thes&w at bass pro
I got to get a new one my buck broke .check out thes&w at bass pro