Dexter HD Suspension & EZ-Flex Install (long w/ pictures)

I've never used the Lippert components, but based on my experience with every other trailer I've ever owned, whoever wrote those instructions was a technical writer that had no idea what the serrations are for. As you said, these should lock into the hanger, not the bushing. I would think it was a typo, but it repeats the same error at least twice.