The pressure gauge does not sit where it should
The needle sits well below or above the marked zone during a shot, or does not move at all.
Applies to: Espresso machine, Espresso
Likely causes and adjustments
Try one adjustment at a time so you know what actually changed the result. Start with the first cause below — if it doesn't help, reveal the next.
Cause 1 of 4 · Commonly the cause
The gauge is showing boiler pressure rather than brew pressure
Does the needle move when you open the steam valve rather than when you brew?
Some entry-level machines have only a boiler gauge, which behaves quite differently and says nothing about what is happening at the puck. Check the manual for which it is before drawing any conclusion.