La Marzocco GB-5/FB-80 Steam Valve Stem (5 O-ring Version) Current-style steam valve stem for the GB-5 and FB-80, used on machines from serial #5000 onward as well as on earlier valves that have been retrofitted to the 5 o-ring configuration. Machined with an M4 hole for the shaft spring guide. COMPATIBILITY Fits: La Marzocco GB-5 and FB-80 steam valves, serial #5000 and later, or any valve retrofitted to the 5 o-ring version Replaces: La Marzocco part # A.1.002.01 INSTALLATION A moderate DIY job for someone comfortable disassembling a steam valve; verify o-ring count matches this stem's 5-o-ring design before reassembly. PRO TIPS If you're retrofitting an older 3 o-ring valve to this stem, you'll need the full 5 o-ring set to match the new stem's groove count, don't reuse the old o-rings. The M4 hole is there for the shaft spring guide pin; confirm it lines up with your valve body before final assembly, as mixing pre- and post-retrofit parts can leave the pin misaligned.