How to descale and service a Gaggia Classic / Classic Pro

This guide covers descaling for the Gaggia Classic — including the original Classic (pre-2015), the post-2015 Classic, the Classic Pro (2019 onwards), and the Classic Evo (2022 onwards). The Gaggia Classic is one of the most-modded home machines in the world and Coffee Parts services more of them than almost any other single brand. The article uses Cafetto descaler — safe across the aluminium boiler that's the defining feature (and limitation) of the Classic line. It walks through the descaling procedure honestly: the aluminium boiler is the part that scale will eventually destroy if water management is ignored, and the Classic's small reservoir means descaling cycles are quick. The article addresses the specific Classic questions Coffee Parts gets most often: the post-clean three-way solenoid stick that's almost a rite of passage, when a heavily-scaled Classic needs a boiler swap rather than a chemical clean, and which generation of Classic you actually have if you bought it second-hand (the part numbers and procedures vary subtly across the four generations). Cross-sells include Cafetto descaler, the well-stocked Gaggia spare parts inventory at Coffee Parts (gaskets, shower screens, solenoid kits, OPV springs), and the popular Classic upgrade parts — pressure gauge kits, PID kits, Coffee Parts silicone gaskets that outlast the OEM rubber by a wide margin.