dishwasher does not drain all the water out.

[tails]

When the dishwasher is done there is water left in the bottom of it.
I have watched it drain a few times and I think it drains slow.
Whirlpool built in mod# du912pfgt2
We can't afford a new dishwasher, so I'm hoping with a little help I can fix this one.
Is it worth fixing?

[tgoods]

Check the airgap at the top of the sink.  I usually find toothpicks and chicken bones there.  Then check the the check valve at the pump (pictured below).  The rubber feet from cutting boards like to find there way in there.  That covers about 95% of the slow drain problems on these dishwashers.

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