Don't know if you can buy the parts separately but I believe Century is owned by Schneider Optics. I know some people have sent their lenses in for mount conversions or repair at least.
The other option is just to take it to your local camera shop. If it's something as simple as broken or missing grub screw they should be able to sort you out. Search online for a manual or assembly diagram. Other than that you'll have to wait to see what the dealer says.