SPA392 Series – How to Replace Mixing Valve CartridgeCreated OnOctober 9, 2025Last Updated OnOctober 9, 2025byAva Campbell You are here: Main Shower Panels 392M/392B/392H/392R/331B SPA392 Series - How to Replace Mixing Valve Cartridge < All Topics Turn off the main water supply. Remove the mixing valve knobs (hot and cold) using an Allen key. Gently rotate and pull out the cartridge. Insert the new cartridge.