If you have never opened up the drain of your dishwasher to clean, you must do it. It is life changing. Remember I have two small children. I clean up boogers and poop all day. I catch vomit in my hands regularly. The stuff inside the drain of my dishwasher was by far the the grossest thing I've ever seen or touched.
I have a newer dishwasher so I didn't have to unscrew anything. The plastic pieces just popped apart.
Ugh the things I saw cannot be unseen.