Dishwasher no longer cleaning dishes

I have no prior experience fixing any appliance but figured I might be able to save this old dishwasher. I read some where on this web site that I needed to replace the upper and lower spray arm, and someone suggested replacing the filter as well. I ordered the parts by looking at partselect.com's picture of the dishwasher and read someone's explanation that I needed to remove the filter housing to replace the filter.

The upper spray arm comes off by gently pulling down on the spray arm. I put the new one in its place.

The lower spray arm had a thin, large (about 2" diameter) round screw holding it and its housing in place. I removed the large, flat screw and the lower arm came off. Below that was the filter housing. I unscrewed the six screws, took off the housing, replaced the filter, and put the housing back on.

Then I removed the lower arm from the plastic thing that was holding it, removed the stainless steel heat plates and put them on the new washer arm. Put the washer arm back on the thing that held it, and screwed the washer arm assembly in place with the large plastic screw.