Where to find it?

Have you looked at the documentation that came with your rig? My new Jayco had manuals for all vendor components that were used in my trailer. Both user, maintenance, and installation. Naturally it depends on the component and the vendor, but most were complete with exploded views, part #,s and any thing else you would need to know. The Dexter axle manual is especially complete and concise. My manuals fill a 3 inch binder.
I just glanced at the Heritage Glen site and your trailer comes with EZ Lube axles which is a Dexter product.

http://www.dexteraxle.com/home_