Lift the lever to around halfway. When you reach that half-way point you will feel an increase in the resistance
to the movement of the lever. A slight amount further is where preinfusion will begin. To verify that
you are a the correct position, watch the brew pressure gauge (the one
on the right), and you will see the water pressure drop slightly when you
have moved the lever the correct distance.
You have opened the brew valve inside the group that allowed water in
the thermosyphon tubes to enter the portafilter (see Chapter 3 for details).
The pressure in the plumbed line is now pushing water into the boiler and
then into the portafilter at low pressure. The coffee is getting wet.