They weren't trying to void the warranty, they just didn't want to honour the 2014 2yr extended warranty. It was just over a year old and they were trying to tell me the 2yr didn't apply to the attachment even when I showed them the printout.
I told them to call me if they couldn't get the claim covered and never heard back from them.
This housing doesn't have any diagram in it to show alignment. Maybe they added that later due to problems? If they've re-designed like in your images at the top of page, I would think the design was problematic.
As I mentioned, either they did not actually change the pump, or they did but aligned it the same way the original had been (wrong). That is the only way I can see that the unit behaved exactly the same before and after the dealer service. Some testing would have shown them this, but I don't think they did any before or after.
But this was not my first struggle with this unit. Previous to the pruner attachment issue, the combi engine fuel cap seized. This recall was the problem:https://www.stihlusa.com/information/recalls/toolless-fuel-cap/
I had to pay for a new cap as the Canadian dist. said it was a US only problem (like we don't have ethanol in the fuel here
Sorry if it seems like I'm bashing the brand or dealer, I work in service in a different field and am pretty understanding of the concerns. However, I also realize sometimes you have to take some losses to keep the customer happy. I'm not hard to please.