Billhook on a Case 8530 Inline small square baler

I ran into some tying issues with my first cutting of hay.  The roller cam on the back of the billhook has gone missing.  I figured the shaft had broken off.  On inspection today, the shaft there is fine, there is a groove for I assume a retaining ring, and the end of the shaft is domed and smooth.  Looking at Messick's, and the AGCO parts diagrams, they only list the entire billhook assembly.  Does anybody (Maxzillian) know if this roller/retaining ring is available separately?  Or the needle/roller/ring assembly?  

 

Thanks.  

 

Reed

 

Billhook on a Case 8530 Inline small square baler