Marette P Falmouth , MA May 13, 2020 Appliance: Thermador SGSX304ZW Thermador Sgsx304zw: Broken knobs. How to replace Cooktop Control Knob. Bought new knobs, these were very hard to find for my product. Your site was easy to use and found the right fit. Thank you! Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes