Water backing into reservoir when brew lever activated [Rocket Mozzafiato R]

[wicked abyss]

Sounds like a non-return valve isn't working right

[azure coral]

i did changed both of them, one at the t fitting at the boiler fill solenoid and the other one at the boiler. or do you mean any other valve?

[wicked abyss]

Whichever one is between the pump and the boiler/hx is the one likely at fault here

it's bubbling back through the pump