Your coffee used to taste better? Check this hidden part of your machine

Your coffee machine was a big purchase, and for the first few months, every cup tasted just right. But lately, the flavour seems flatter, sometimes even bitter. Before buying new beans or fiddling with the grind settings, it might be worth looking at something you haven't checked in a while.

Most owners know to empty the drip tray and run the descaling programme when the warning light comes on. But manufacturers recommend other maintenance jobs that don't always come with a convenient reminder.

One of them involves a part hidden behind the service door of many bean-to-cup machines. If you've never opened that door, you might be overlooking a simple step in your cleaning routine.

The part manufacturers say to clean regularly

It's called the brew group, the unit inside the machine where the coffee is pressed and brewed. On many fully automatic machines, you can remove it for cleaning.

The Philips 2300 and 3300 series manual recommends rinsing the brew group under the tap every week and cleaning it monthly with a coffee-oil remover tablet.

For the weekly rinse, remove the unit as instructed, rinse it thoroughly with water and pay attention to the upper filter. Let it air-dry before putting it back; Philips advises against drying it with a cloth because fibres can collect inside.

The monthly tablet treatment removes coffee oils that water alone may not clear. The procedure varies by model: some machines use a dedicated cleaning programme, while others require a tablet to be dissolved in hot water before the filter is cleaned. Follow your own manual rather than assuming every machine works the same way.

Don't forget the other maintenance jobs

Rinsing the brew group isn't the only task that can get overlooked. Philips also recommends lubricating the brew group every two months on the 2300 and 3300 series, using its specified grease on particular moving parts. Check your model's instructions before doing this.

Other parts need regular attention, too:

• Drip tray: Empty it daily or when the machine indicates that it is full.
• Coffee grounds container: Empty it when prompted and clean it weekly, following the manual's instructions.
• Water tank: Rinse it weekly.
• Milk system: Clean it after use according to the manufacturer's guidance. Philips recommends rinsing its LatteGo system after every use.

De'Longhi's machine-care guide highlights three common maintenance concerns: coffee oils, milk residue and limescale. Its guidance also says to rinse the brewing unit under warm water and avoid detergent or solvents on it.

Check your model before cleaning

Not every bean-to-cup machine has a removable brew group. Some rely on built-in cleaning programmes, and instructions can differ even between models from the same brand.

Before opening the machine, check whether the unit is removable, which cleaning products are recommended and whether any parts are dishwasher-safe. Never assume soap or a general-purpose cleaner is suitable.

Before you blame the beans

If your coffee tastes different, start by checking whether routine cleaning is overdue. Clean the removable parts your manual identifies, check whether a coffee-oil treatment or descaling cycle is due, and make sure the milk system is clean if you use it.

A dirty machine isn't the only possible reason for bitter coffee, but maintenance is a sensible first step before changing your beans or grind settings. Your machine's manual may contain the answer you've been searching for.