My Gaggia Classic is having an issue where, when the machine gets very hot, there is no flow at all through the group head. The pump is working, as I've got steady water flow through the steam wand at all times. And if the machine isn't too hot, i.e. if it's been on for only 10 minutes or so, I get what appears to be normal flow from the group head. If left on longer, it gets hotter and when I try to brew the pump is reduced to a hum and there is no flow at all from the group head.
I've descaled and backflushed the machine. I've also cleaned the shower screen and screen holder, as well as disassembled, cleaned and replaced the three way solenoid. I'm at wit's end. Any ideas?
There is a "Steam cap" above the "brew block"
in the Gaggia (all of them in fact..)
It is a ball bearing or rubber bearing on
a spring that keeps steam from coming
out of the brew head when the machine is
in steam mode --
Normally, when the machine is in brew,
there is more than enough pressure to
push the spring and bearing out of the way
so water can get through.
Entirely possibly it is sticking when the
unit gets too hot.
That water moves freely out the steam wand
and the pump sounds normal are valuable clues.