> Are you referring to the stainless steel filter in the sump?
Yes, that and the perforated grey plastic cup under the inlet cover, called the "filter sump" in the parts breakdown.
> On page 17 of Technical Service Guide 31-9083, they refer this this piece as the "fine filter." Yet, on the parts breakdown, page 35, they refer to it as a "coarse filter." Why can't they make up their mind?
That's why I used the "reference numbers" from the parts breakdown in my original post! :-) I think they screwed up the picture and text on p. 17-19, the "cheesy nylon filter ring" is called the "fine filter" in the parts breakdown. The names for both of those in the parts breakdown make more sense, to me.
> If you want to remove the schizo filter, you're on your own. I've never done that on these dishwashers. Never needed to.
Okay, thanks. Well, now I have removed both of them, and it's clear that I certainly needed to! There was an accumulation of white gookus on the underside of the stainless ("coarse filter") screen, up to about 3/4 inch thick, that completely blocked more than 1 square foot of area of the filter and filling the space between the screen and the tub bottom. The "filter sump" was also still quite blocked. I'm fairly certain the pump was cavitating due to low flow (a surging of water and motor sounds every second or two while running), that is completely gone after cleaning it.
For the benefit of others in the same situation, here's how I removed them: Follow instructions elsewhere to access and remove the inlet cover, such as Samuri's above. The filter sump holds down the screen, so it needs to come out first. The filter sump has two plastic catches, one on each of the front and rear sides, that lock into catches on the plastic tub. You can't see them before you take it out, unless you have the newer updated filter sump. You may be able to squeeze the sides together using the "ears" that the inlet cover clips to and pull up. Mine wouldn't budge. So while squeezing the sides and applying an upward pull, I ran a small, long screwdriver down between the screen and the plastic cup. Doing this on the front and rear sides released the filter sump cup. Then the coarse filter screen can be removed. Chunks of white gookus may fall down into the inlet sump below, so crawl into the tub with a light and clean them out so they don't go through the pump, plugging the holes in the spray arms that you previously cleaned trying to fix this problem before.
I used a putty knife to gently scrape the gookus off the screen and cup, and then lots of hot water and a stiff scrub brush, and soaked overnight in vinegar (not sure that last part really helped.) I used a pointy tool (awl) and/or toothpicks to clear the more stubborn holes in both parts. To reassemble, reverse the steps.
Lastly, I followed the Deadly Mistakes link above posted by Samuri and ordered the Finish Powerball tablets mentioned in Deadly Mistake Numero Uno. I hope Samuri gets something for the referral. Then I ordered the new updated filter sump from RepairClinic, which is almost all holes instead of the measly 2 square inches mine has. I still need to order some sort of dishwasher cleaner as mentioned in Tip #2 on the Deadly Mistakes page.
I feel I've taken the first steps towards enlightenment. Sorry for the long post. Thanks all for the help.