The later guns are a little different from the HD and the offered schematic would probably not be useful enough.
You can get parts for the HD at Brownells but they don't have a schematic on their site. Numrich lists the parts and have a schematic for sale at $.99. The schematic is also suppose to be in their large gun parts catalog.
Numrich is also know as Gun Parts:
http://www.e-gunparts.com/schematics.asp
(For the schematic.)
LDBennett