Bought this dishwasher from Sears in late 2015. Very recently the dishes has not been coming out clean, instead having soap particles or other debris on the dishes, especially on the top rack.

I positioned the top sprayer arm in a specific spot, and ran the dishwasher. After a few minutes I opened the machine and the top sprayer arm had not moved. It was certainly spraying water, as the dishes were wet and the arm was covered in droplets. Thus I do not think it is a water pressure issue. To double check this, I removed the top rack and with my garden hose shot high pressure water through the sprayer arm intake, and the water shot up and out the holes on the arm, but the arm did not turn whatsoever.

The dishwasher is still in almost condition, we always clean out the filter. The sprayer arm seems to spin freely by hand. If anything it's very loose. I can't see any means of tightening the sprayer arm where it attaches to its hose. See attached pics, showing the white circle thing around the arm center - that white piece spins freely by hand. What makes the sprayer arm spin, is there an impeller or water pressure driven gear?

On a separate matter, I would like to clean out the arm, as I see one small food particle in one of the spray holes (look like a piece of oatmeal, though not sure how got past filter, likely machine was run without top rack firmly against aft wall where sprayer arm intake connects to pump), but I can't figure out how to separate the top and bottom sections of the spray arm.