This section is not meant to be a replacement to the FSM.
It is meant as a compliment to the FSM with added information with pics that are not in the manual.
Always buy an Factory Service Manual AND a Factory Parts Catalog to help you along your maintenance path.
The Haynes and Clymer brand service manuals for the most part will suffice and they generally have more pics than the HD Service manual.
But the HD manuals will be the most accurate.
All in all, there are discrepancies in all of them including the HD parts and service manuals though.

With some of these parts, finding imperfections and cracks requires more than just glancing at them for obvouos damage.
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• Gear Dog Damage: Inspection and Causes