Thanks.
Yes I checkted all the parts to be in the right place - I took them apart and reassembled for testing.
No, I didn't measure the real temperature. Although I'm quite sure since when displaying 150° the material keeps hard and solid inside the nozzle, when displaying 260° it behaves like 150°: Some can be pressed through the nozzle with much effort, but makes not a propre "thread".
In the meantime I bought a "hot end bundle" and had some more unhappy experiences, but I'm gona open a new thread here....