Every failed shot is information. Here's the troubleshooting guide we wish someone had handed us with our first machine — symptom, cause, fix, in the order of likelihood.
First, the master table
| Symptom | Most likely cause | Fix |
|---|---|---|
| Sour, thin, fast shot | Under-extraction | Grind finer |
| Bitter, harsh, slow shot | Over-extraction | Grind coarser |
| Sour AND bitter | Channeling | WDT + level tamp |
| No crema | Stale beans | Buy fresher (roast date!) |
| Spraying from portafilter | Uneven puck | Distribution + tamp |
| Weak body | Dose too low / ratio too long | 18g in, stop at 36g out |
Sour or bitter: the grind dial is the answer
Ninety percent of taste problems are extraction problems, and grind size is the main lever. Shot ran 15 seconds and tastes like lemon water? Finer. Dripped for 45 and tastes like ash? Coarser. Adjust one step at a time, change nothing else, and log it — this is dialing in, and it converges within a handful of shots.
Sour AND bitter together: channeling
Water found a crack or soft spot in the puck, over-extracting that path and under-extracting the rest. The fix is prep, not grind: rake grounds with a WDT tool (the single best $25 in espresso), then tamp level — a calibrated tamper removes the guesswork.
No crema: it's the beans, almost always
Crema is CO₂ emulsion, and CO₂ leaves beans within weeks of roasting. Supermarket beans with no roast date are typically months old — no machine can foam gas that's already gone. Buy bags with roast dates under 3 weeks, and store them well.
Everything slowly got worse over months
That's not technique — that's rancid coffee oils coating your group head and shower screen. One Cafiza backflush and a screen soak will shock you (the water runs brown). See the full maintenance schedule; a clean machine is a permanent prerequisite, not an upgrade.
