Mineral build-up in the nozzles and capsule cage of a Nespresso D150 coffee machine can cause a drop in the machine's performance. In extreme cases, the machine may be prevented from making coffee entirely. Fortunately, it is possible for you to clean this type of build-up.
Turn the machine off and unplug it.
Clean the steam/hot water nozzle with a damp cloth. If the nozzle is blocked, unscrew it using a coin and use a needle to remove the residue causing the blockage (see Reference).
Remove the integrated frothing attachment from the bottom of the nozzle by unscrewing it with a coin (see Reference).
Rinse the nozzle and the frothing attachment in hot water (see Reference).
Re-attach the frothing unit, then screw the nozzle back in place (see Reference).
Turn off and unplug the machine. Take off the water tank, drip tray and capsule holder (see Reference).
Wait for the machine to cool down. Once it has, turn the machine upside down. Take the hexagonal key that came with the machine and place it in the capsule holder. Turn the capsule cage's handle counter-clockwise to unscrew it (see Reference).
Unscrew the capsule cage completely, then rinse it in water. Use the cleaning tool included with the machine to clean out the holes on the water spout. Also use it to clean the water entry point of the capsule cage (see Reference).
Look at the arrows on the capsule cage and blow in the direction they are pointing. This removes any deposits from the cage. Use the cleaning tool to clean out the holes a second time, then blow through the capsule cage again (see Reference).
Place a light coating of lubricant on the capsule cage threads. Using the hexagonal key, screw the capsule cage back in place (see Reference).
Always remember to unplug the machine before attempting to fix it to lower the risk of electrical shock.