You just need to do routine maintenance, which we all tend to avoid until there is a problem. I once got gunk in the rotating spray wand, clogging the holes, and it took FOREVER to clean it out.

I think I know what you are talking about. I take my assembly out once a month or so and rinse in hot water and with the sink sprayer on that perforated part. I think you could soak it in vinegar. Maybe use an old toothbrush too. Vinegar might dissolve some of the junk. You can soak your bathroom faucets in it to clear junk our of the nozzles so why not give it a try. Should freshen too.

Most dishwashers have food filters that need to be regularly emptied and cleaned. Like monthly. It sounds like that's what you're dealing with, the gunk may be what's accumulated because you haven't been cleaning it.

Find the owner's manual for your dishwasher and follow the instructions for keeping the food filter clean.

Put it in a bowl of hot water and add a denture cleaning tablet it will fizz it out.

Also good to soak it in would be dishwasher detergent which contains enzymes or this spray for showers called clean shower. Put it in a bowl and spray till saturated and let set.

Whens the last time you ran the clean cycle with citric acid? It should be done regularly. The manual should give you directions on the clean cycle and cleaning the filter. If you no longer have a manual you could go to automaticwasher.org and ask. Those guys know everything about every dishwasher on the market...ever. in the meantime I wouldn't use it because of the risk of bacterias.

That round disk is it just the protective screen or the actual filter?

What make and model dishwasher do you have, I think few come with macerator/grinder any more. Since so many value silent dishwashers, most have a filter that needs manual cleaning periodically. If that's what you've got, but you don't have the book, instructions are easy to find online, google make, filter, maintenance or cleaning. Mine is the older style with grinder, and I don't care that it's not all that quiet. It gets the dishes clean and dry, and even with water not high in minerals I do run an Affresh tablet through it every once in a while - I keep them on hand for my washer and my dishwasher.

https://www.youtube.com/watch?v=N33EFLw8eQ8

Graywings.....Thank You! I've been having trouble with my dishwasher not doing a great job. I clean the filter regularly but never thought about the spray wand. Removed it and sure enough, several holes were clogged. I took a nut cracker pick and cleaned them out. Dishes are much cleaner now.

Everyone should be running a clean cycle thru their dishwashers every other month using citric acid. Most grocery stores sell it along with Home Depot and Lowes. Directions are on the package. Not cleaning them regularly is the biggest cause of dishes not getting clean and for early death.