I have a breville barista express (bes870xl) at home, which up until a few weeks ago was making surprisingly good espresso.

Now its not building up pressure, theres a buzzing sound (not the pump, the steam and water outlet both work fine) and water is being pumped into the drip tray as well as the brew group with not even enough pressure to make the espresso.

I figured it just needed a descale so i did the usual dezcal and clean water flush, and it solved the problem for a little bit, but now the problem's back and cleaning didn't fix it this time. Looking inside the machine I don't see any evidence of scale on the silicone tubing or anywhere else.

Could this be a bad solenoid valve? or what else could it be?