Here is a typical illustration we see in owner's manuals and product instructions. 

However, being typical doesn't mean it can't be improved. 

How would you polish it? 

One key readability issue lies in the back and forth lookups, between index numbers and the actual meanings, which is hard to follow, easy to lose track of, and requires heavy eyeball travels. 

Hence this idea below to annotate directly in context. 

That's exactly why 3DEXCITE Product Communicator CATIA Composer SOLIDWORKS Composer xHighlight provide this type of in-context annotations. 

Sleek and straightforward, especially in this BeforeAndAfter comparison. 

Even better, these in-context annotations are linked to component properties, so that they update automatically per property updates. 

Hope you find this style easy to create and your audience finds it more readable.