Whirlpool does not drain properly

Hi,

This dishwasher left water on the bottom, did not drain it in one cycle. I had to run the “drain” 4 or 5 times to empty it out.

I took everything inside apart and I only found a pit and a plastic piece of a broken knife-handle; they were hold inside “item25” (see the drawing Replacement parts for WHIRLPOOL DU600PWKQ0 | AppliancePartsPros.com ). I inspected every item and there was nothing broken, I couldn’t see anything unusual.

I thought this was the problem and I put everything back, with the huge help of the drawing mentioned before (I would have been lost without it).
I didn’t break it more but I didn’t fix it either. It still doesn’t drain the water.

I checked the hose from the dishwasher to the garbage disposal and it’s OK. Every cycle work fine, except the drain part.

Where else can I look? I suspect now the drain valve (item 15 in the drawing). How do I test it?

I am up for any sugestions, it will be a shame to get another machine, this one used to work so well…

Thank you in advance!

no idea, anyone?