Bonjour,
Many thanks Richard for your help, you even learnt me something today !
However, I hope that the videos show what happened to my ferule and pipes, gnawed and full of a blank stuff as hard as stone.
As I am not equipped to re-weld a new ferule (I can build a new pipe to the regulator hopefully) I have been obliged to undress the boiler to send ot back to JMC the manufacturer :
https://www.jmc-vapeur.fr/ our last one in France after Anton retirement.