I'm glad you admit "I'm trying to understand what happened".

I'm not happy that you blindly defend CEL just because you're a payed contractor in the US.
There is really a list already of people that are
1. are happy with your technical input
2. laughing their ass off when you defend CEL time and again while not knowing all the facts or just make things up as you go

So you point out ANOTHER mistake from support: they forgot to tell me there are more then one seal, and that PERHAPS they opened another seal.
The seals were not the original problem.

You see, the point remains the same:
the ASKED a customer with no knowledge if they needed to repair a print head of 3 years old,
which they state themself is by their definition end of life.
Did they give me that information ?
NOPE.

They only asked the money and got paid for a useless repair and gave me back a worthless print head.
Don't degrade yourself in defending this.