This is often unnecessary on newer Stern Machines as the coil stop is the weakest link as the brass rivet on the coil stop often times break before there is any wear on either the coil stop itself or the plunger.

Unfortunately this is not even guaranteed with a new flipper mechanism in a new Stern machine; I've replaced broken coil stops in machines that were less than a year old.

I have no doubt you are very experienced here, unfortunately your experience is working against you as the the most common flipper related problem on newer Sterns (Spike and later SAM) is that the coil stops actually break with zero wear to the actual stop itself or to the plunger. Now I do replace the coil sleeve as well since there is no reason not to; and I never replace the EOS switch on these newer machines (unless its physically broken) as there is just no reason to.

I'm sure there will be a time that an entire flipper rebuild will be needed; granted I don't know for sure that the OP's HUO machine doesn't have a worn plunger, but I'm willing to bet it doesn't...I'd also be willing to bet there is a small pile of brass dust in the bottom of the cabinet under the flipper that's having an issue.