The top rack will not wash. I have cleaned the spinning arm and the tubing going to it. Nothing in it. Why would the top rack not wash and the bottom was fine?

Probably something clogging the drain inside the machine. You will need to locate the drain in the bottom of the tub at the back. It will be under a plastic grid. Carefully take the plastic grid off. I used a 6" plunger that had the wooden handle sawed off. Carefully plunge this drain. The water will come out the middle water tower. You can actually reach your hand down into the drain and physically remove any debris. I recommend using a fine tea strainer to remove any debris from the water. Plunge several times and remove all debris. Apparently there is something clogging the upper arm which keeps it from spinning. Have you taken toothpics and cleaned every one of the holes in the arm? Try that before plunging anything. You probably have debris in the holes in the top arm if the bottom arm works OK.

I just had a service guy fix the very same problem. These machines cannot handle debris bigger than a small olive pit. These items simply accumulate at a grid that protects the macerator until they block the water flow. You have to unscrew the disc at the bottom of the machine (beneath the bottom swing arm) to get at it. Older machines had an easily removable debris basket. You popped it out, dumped the debris in the garbage and replaced it. Some bonehead decided to dispense with that. I'm told the Europeans have gone back to the old-style removable debris basket. A real no-brainer.