A shot that dribbles out weakly, or a pressure gauge that never climbs into the normal range, almost always traces back to one of these. Work through them in order — puck-related causes are both the most common and the easiest to rule out first.
01Grind too coarse
This is the single most common cause. A coarse grind offers too little resistance, so water rushes through without the puck ever building back-pressure. If your shot pulls in well under 20 seconds, start here before suspecting the machine at all.
02Dose too low or puck not tamped evenly
Too little coffee, or an unevenly tamped puck with channels running through it, lets water find a low-resistance path straight through — same symptom as too coarse a grind, different cause. Weigh your dose and check that your tamp is level.
03Worn or scaled group head gasket
A gasket that's lost its seal lets pressure escape around the portafilter rather than through the puck. You'll often see water spray from the sides of the portafilter during extraction — a strong sign to check the gasket.
04Scale buildup restricting flow
Heavy scale inside the boiler or flow path can restrict water delivery enough that the pump can't build proper pressure, even with everything else correct. If it's been a while since your last descale, this is worth ruling out — see our descaling guide.
05Failing pump
If beans, grind, dose, and gasket all check out, the vibration or rotary pump itself may be wearing out. This typically shows up gradually over months rather than appearing suddenly, and is a parts-replacement fix rather than a cleaning one.
| Symptom | Most likely cause |
|---|---|
| Fast, watery shot | Grind too coarse or dose too low |
| Spray or hissing at the portafilter | Worn group head gasket |
| Gradually weaker pressure over months | Scale buildup or pump wear |