Product review (5 stars): FREE from Whirlpool. Refrigerator 1.5+ yrs old.
FYI...call Whirlpool main# 866-698-2538. Tell them ice build up on bottom freezer/defrost water does not drain. Give them new replacement part# W10619951 (but they should know). Dont call parts they didn't know what I was talking about then transferred me to service they still didn't know.

They offered to send tech out to do repair for free also but I declined. EZ fix since Ive already took apart the old part to clean. Just Google part# for more info. Found this video useful on YouTube.
https://www.youtube.com/watch?v=Tk24ISRzSRs