My dishwasher has been running well but in the last few months started leaving lots of spots on glassware, plates, and silverware.  I live in Iowa where we get water from lime aquafers so the water is REALLY hard.  I figured it needed a cleaning and tried to take it apart.  I noticed in the bottom bowl many of the 1cm square holes in the grill were covered with what looked like paper, maybe a jar got washed with a label on it or something.  I can't easily clean the grill behind the top cover, I can feel stuff back there but can't see what I'm doing, and there's crud I can see inside the bowl through the grill.

I need to take the cover off the bowl area to clean the back holes in the grill.  I've removed the lower arm (8 T15 screws) but I don't see how to remove the cover itself.  I've taken a wide and tight picture to show what I've got to work with.  After having taken the closeup picture I see more screws under a disc, and there's a large nut on the top of the disc.

I don't want to remove any more parts than necessary for fear of breaking something, making it difficult to reassemble, or causing a leak.  I'm definitely a DIY but I'm out of my comfort zone and get more cautious when dealing with plumbing or automotive. (give me a laptop and I can have it in 200 bits in a few minutes no problem)

I was able to get the inside of the door off and remove that and clean the bottom vents and removed a bunch of caked on detergent below the hatch but there's probably a big mess in the bowl below, around and inside the grill.

I'm new to the forums, the tollfree number here suggested I ask you about this. (was hunting for a service manual, not finding it)  I've attached lower res pictures of where I'm at, and there's a direct link to the folder below that includes high resolution (big) pics if you need a closer look at something.