Robert L Woodruff , UT June 06, 2018 Appliance: Whirlpool Dishwasher WDF540PADW1 Whirlpool Dishwasher Wdf540padw1: The arm spray had fallen off from the top of the dishwasher. How to replace Retainer. I simply removed the washer arm - removed the old cap from the top of the arm and snapped the new cap into the new arm spray- The whole repair took less than 5 minutes from the time I opened the dishwasher until I closed it. 19 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes