The drive coupler was "chipped"
David G. • Louisville, KY • June 21, 2014
Appliance: Whirlpool 5-Speed Blender KSB5OB4
My Repair & Advice
After watching a video on how to remove the chipped drive coupler, the removal of the old coupler and replacement with the new one took about 10 minutes. One of the easiest repairs that I have ever done.