If you have a semi-automatic espresso machine with a 3-way pressure release, or solenoid, valve, you need to backflush it on a regular basis to keep the machine in fine working order. Backflushing will clean up behind the screen and into the brewing system, cleaning out coffee or grounds residue and reducing the potential for clogs.You can watch Dane as he cleans a Rocket Giotto, or follow these steps:
Place 1/2 teaspoon of a backflush detergent such as Cafiza or Joe Glo (Important: make sure it indicates backflushing as its primary use on the label -- do not use Dezcal or any other standard detergent here!)
Insert the portafilter into the brew group and initiate a shot
Allow the pump to run about 4 - 5 seconds maximum
Turn the pump off and allow the water and suds to release through the valve
Repeat this process until the water coming out of the valve is clear and suds-free
Remove the portafilter, rinse it in cool water to cool it down and then switch out the baskets again
Before you pull your first shot, run a blank shot through the system to make sure there is no residue leftover