Troubleshooting

The cup tastes sharply bitter or harsh rather than balanced.

The cup tastes sharply sour or acidic rather than balanced, often alongside a thin body.

The cup lacks strength or body, tasting diluted.

The shot finishes well under the typical 25-30 second window and often tastes thin or sour.

The shot takes noticeably longer than 30 seconds and often tastes bitter or over-extracted.

Water sits on top of the coffee bed and drains far slower than expected, risking over-extraction.

Water blasts through one path in the coffee puck instead of flowing evenly, often visible as an uneven, spurting or fast-then-slow stream.

The espresso shot has little to no crema layer, or crema that disappears very quickly.

Gritty sediment collects at the bottom of the cup, or the brew feels muddy rather than smooth.

The coffee tastes sharply bitter or has a burnt, scorched character.

Steamed milk stays flat with little or no foam forming.

The finished cold brew, after normal dilution, tastes noticeably weaker or stronger than expected.

The cup feels overly intense or concentrated, distinct from tasting outright bitter.

A sharp, acrid, ashy or scorched character rather than balanced roast flavour.

The cup lacks aroma and lively flavour even though strength and ratio seem correct.

After brewing, the spent grounds sit unevenly in the dripper — a dry patch on one side, a deep well on the other.

Milk foam looks coarse and airy with visible large bubbles rather than smooth, glossy microfoam.

Milk tastes scalded or unpleasantly sweet-burnt, or is uncomfortably hot to drink.

A hot coffee drink cools down faster than expected before it's finished.

Flow has slowed noticeably over time, coffee tastes increasingly off regardless of recipe changes, or visible mineral scale is present.

Ground coffee looks uneven, with a visible mix of very fine dust and larger fragments at the same setting, or the same setting produces noticeably different results from one grind to the next.

The foam holds its shape like meringue and sits on the coffee as a separate layer instead of folding into it.

The milk pours like hot water, with no foam to speak of and no weight in the mouth.

The milk separates into flecks or a grainy layer where it meets the espresso, sometimes within seconds of pouring.

Instead of a pattern, a pale round patch of foam lands on the surface and stays there.

A pattern appears while pouring and blurs into the surface within seconds, or never shows clearly against the crema.

Steam comes out of only some holes, sprays sideways, or the flow is noticeably weaker than it used to be.

One or more jets fire sideways from the underside of the basket during the shot, instead of the flow converging into a single stream.

Stirring the grounds before tamping changes neither the flow nor the taste of the espresso.

On unlocking the portafilter, the spent puck has lifted out of the basket and is stuck to the group.

Knocking out the portafilter reveals a sludgy, waterlogged puck rather than a firm one that releases cleanly.

The puck surface slopes visibly, or the shot consistently runs faster on one side than the other.

The puck shows the imprint of the shower screen, or sits so low that water pools above it.

Ground coffee comes out in visible lumps rather than as loose grounds, particularly at espresso settings.

Grounds cling to the chute, jump out of the cup, and scatter across the worktop.

Less coffee comes out than went in, and the first dose after a change of bean tastes of the previous one.

Grinding the same amount by time or by the same number of turns produces a different weight of coffee each time.

Every adjustment overshoots: the shot is either far too fast or far too slow, with nothing usable in between.

A small grind change produced no effect, or a much larger effect than expected, or the effect arrived a shot late.

White chalky deposits appear inside the kettle or reservoir, heat-up takes longer, or flow through the machine has dropped.

The drinks made after cleaning or descaling taste soapy, chemical or sharply sour.

Fitting a blind basket and running the pump produces no flush, no release into the drip tray, and no visible cleaning.

Steam comes out but the milk warms without ever forming a whirlpool, or the machine runs out of steam part-way through a jug.

The milk produces plenty of foam, but it is airy and bubbly and never turns glossy, however carefully it is steamed.

The needle sits well below or above the marked zone during a shot, or does not move at all.

The ready light comes on quickly but the first shot tastes thin and sour, or the machine needs a long wait before it performs.

Coffee you roasted yourself tastes sharp and vegetal, or dull and papery, despite being freshly roasted and rested.