As an Amazon Associate I earn from qualifying purchases. Two things make an espresso machine taste worse over time. Coffee oil builds up in the group head and goes rancid. Limescale builds up inside, where you can't see it, and blocks valves and heating elements. They need different cleaners, and mixing them up is how people break machines. First, Check for a Three-Way … [Read more...] about Espresso Machine Cleaning Kit: Backflushing Only Works on Machines With a Three-Way Valve