Only theory in my brain- and it worked as I thought it would.
Before buying this, I had only in my mind, the idea of what needed to be done. I must say-its cake. Sure getting a tamp down perfectly every time is tough and will take some time- but in the first day I was making some great shots. This works perfectly. Also for descaling- I see a lot of different information. A brass boiler safe descaler will work) BUT THIS IS WHAT NO ONE MENTIONS- Due to the main boiler cap and steamer threads- it is very easy to rig up a flush from your sink to the unit and then out of the steamer. Let this run for a bit and you are going to get 100% flush of the boiler and sight tube. Not really sure why that information is missing all of the internet- for any of these manual machines really...seemed like a simple idea. It works- and you dont have to shake the machine around like some reviewers mention...which seems totally stupid by comparison. Only thing that seems "cheap" would be the plastic ball valve knob. I am sure this is to insulate the temperature but it would have been nice to see something a little more formal on this machine-perhaps a knob that was more slight.