The steam thermostat controls steaming temperature and consequent pressure. They may "drift" and change state (turn off) at a lower temperature, but that would be my second guess. My first guess is that the steam nozzle is clogged. You can use a safety pin to clean it out. The steam valve controls steam flow; it has a nylon seat and an o-ring. If it's not the nozzle or thermostat, I'd suspect that the valve seat is somehow jacked.
That's a (exploded) parts diagram, not a wiring diagram, not a schematic.
Lorsqu'il en aura reçu, il pourra afficher un graphique de sa réputation au fil du temps.
Voici un aperçu de ce à quoi ressemble ce graphique :
Aucun point de réputation obtenu pour l'instant.