It used to take my a long time to clean dispersion screens. Scrubbing, toothpicks, etc. I finally took them to work and cleaned them in an ultrasonic bath. Eventually I bought one for home and found I don't need an industrial strength version. Here is the one I purchased. https://www.amazon.com/gp/product/B0006DOALG/ It was only $80. This exact one is not currently available, but there are lots of similar choices.

Here is the "before"


The basket holds everything. Even the portafilter, keeping the handle out of the water:


Add a dash of Cafiza and 6 minute runs takes care of it.


Final result: (Brass heat sink is still a little tarnished, but no coffee residue)

Great tip!

I noticed that you have a Vivaldi grouphead with IMS shower screen. I'm curious what your usage pattern is and how often you backflush with water and calfiza since I've never seen that much build up on my shower screen and group head water dispersion disc since I switched to IMS shower screens.

My normal routine is 2 espresso/day, short water flush and light scrub with pallo brush after each shot, backflush with water after my 2 shots each day, backflush with calfiza once a week. After 2 months, when I last disassembled the shower screen and dispersion disc to see how well the routine works, it still looked as good as new after I had backflushed with calfiza.

hmm, interesting! I make perhaps 4-6 a day. I run some water and also backflush after every shot, and even wipe the screen after the shot. Maybe I have a bad fit or something. I don't backflush with Cafiza very often, however.