Ken L Nutley , NJ January 20, 2019 Appliance: Whirlpool Dishwasher WDF520PADM5 Whirlpool Dishwasher Wdf520padm5: Drain hose with check valve wasn't working and the drain pump wasn't working. How to replace Drain Pump. Replaced the drain pump and drain hose and the problem was fixed. 4 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 15-30 minutes