I have hard water and have started using 'Dishwasher Magic' Amazing stuff.
I recently noticed food debris on some dishes.
When the arms stopped spraying, I started to trouble shoot after checking the manual on this site.
First filter was packed solid. could not readily remove it to clear but after hours finally cleared this area.
Diagram was not clear on the names of parts nor on what they should look like.
I also chipped away mineral deposits from other removed parts. Wow almost a pound.
I reassembled ( manual was less than helpful here) and tried DW with no arm spray.