Rancilio Steam/Water Valve Knob Retaining Nut The small nut that secures the steam or water valve knob onto its stem on the newer-style Rancilio Epoca and Classe valve assemblies. A cheap, easy fix when a knob is loose or wobbling. COMPATIBILITY Fits: Rancilio Epoca and Classe steam/water valve assemblies, new (post 2007/2008) version only Replaces: Rancilio R_606 INSTALLATION Simple DIY swap with a small wrench. PRO TIPS Before assuming you need a whole new valve, check this nut first, a loose or stripped knob nut is one of the most common causes of a steam knob that spins without actuating the valve on newer Classe/Epoca machines.