Whirlpool Quiet Partner II - Identify gasket from lower sprayer arm area

[Sonics]

Model Number: Quiet Partner II
Brand: Whirlpool
Age: 6-10 years

Hello, I heard a humming noise from my dishwasher, disassembled to clean out the chopper assembly and this part below was floating inside where the lower sprayer arm section locks into place.

I'm hoping for help in identifying and reassembling if necessary. I've looked at a few diagrams and nothing resembles this part.

[Doc Ryan]

What is the model number of your dishwasher? Click here for common locations to find the model number tag.