Problem: Dishes in the top rack no longer are being washed

The motor on this model still works great, but I am wondering if it is suppose to reverse its direction to shoot water up to the top rack.
The motor has 110vAC going to it when it is running.
The impeller shoots water into a small area with two water outlets - one for the bottom rack and one for the top rack. In this same small area where the water is being shot into there is a plastic ball that seems to always block the outlet to the top rack. I figured that the motor may have to reverse and that may somehow pull the ball away from the top outlet and send water up the pipe. With the ball removed there is not enough power to shoot water to both the lower and top racks.
I have attached a drawing that may help. # 58 is the plastic ball, #10 is the small area where the water is shot into and the bottom rack outlet, #32 is the oulet to the top rack.
Any knowledge/ideas would be appreciated. Thank you.

Yes I uderstand that, but HOW is this accomplished. Does the motor reverse? The plastic ball always seems to be blocking the water outlet to the top rack.

I took another look at the "ball' setup. The ball is actually sitting on a slope with the upper spray arm's water outlet at the bottom of the slope. The "ball" would have to move up the slope in order to block the lower spary arm's water output. The slope is made up of two separate walls with a space in between them and the ball rolls along the edges of the walls.
The motor also has a circuit board attached to it which is why I thought the motor may reverse itself.
If this is not a motor issue then I am having a heck of a time trying to understand how that ball is moved up a slope. Thank you.