I cannot find any info using the given Model Number. please check it.

The rinse aid is usually either opened mechanically or by a wax motor.
This is sort of like a solenoid in that a plunger moves in and out.
This is accomplished by melting wax it expands and and pushes the plunger out.
If the little heater in the wax motor burns out the of course it no longer works.

Have you changed detergents lately?
Try draining some water out of your hot water take. Let it run till it is clear.
Here is a good link, Take a look at #28, #22 and #7
http://www.applianceaid.com/dish.html