Product review (1 stars): Do Not Buy
In addition to Whirlpool units, this part is also used on Frigidaire units and the Kenmore 12773 dishwasher. As mentioned by other users, it will fail at about the one year mark. Replacement rack adjusters will also fail around the one year mark.  The part has small plastic tabs that hold the wheels to the rack adjuster.  These tabs will deteriorate in the hot environment of the dishwasher, causing them to fail.

Without a doubt, this design is faulty.

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Edit 02/03/2015
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Everyone posting here should file a complaint with the Consumer Product Safety Commission.

www.cpsc.gov

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Edit 02/26/2015
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DO NOT BUY THIS PART!

Search for "W10712394 Dishwasher Adjuster Replacement Kit, Replaces Both W10350376's".  It is a permanent solution and less expensive overall compared to the cost of two plastic adjusters.  For some strange reason, this part is listed under the Industrial & Scientific section and it does not appear in the purchasing list when you search by the part number alone.