Bruce D Cumberland , RI January 24, 2023 Appliance: Whirlpool Washer WFW9400SW01 Whirlpool Washer Wfw9400sw01: Whirlpool washing machine leaking.: code f21/sud. How to replace Filter Cap Seal. Replace all hoses, cleaned filter and all elbows/inlet ports The repair could have been much quicker had all ( squeeze ) hose clamps be facing toward the front of the machine. Suggest checking and cleaning all elbows and external drain hose for gunk before buying any replacement parts. Do-It-Yourself Rating: Repair Time Estimate: 1-2 hours