Dishwasher not cleaning

MY MAYTAG QUIET SERIES 300 DISHWASHER DOES NOT COMPLETELY DRAIN WHEN WASH CYCLE IS COMPLETE-OTHERS HAVE SUGGESTED VINEGAR & CALCIUM BUILD-UP---WHAT SHOULD i TRY?

Lack of salt in the dispenser !
It needs topping up !
It will take a couple of washes for the system to get itself back to normal.

Some questions:
- Did you changed your detergent to a new one?
- Do you strict to add salt (washing machine salt and not cooking salt!) at time. Its effects water hardness.
- Do you strict to add the rinse aid at time.

The dishwasher salt response is acceptable for Europeans, but U.S. dishwashers do not have a salt dispenser, nor is dishwasher salt sold in U.S. stores. U.S. consumers should descale their dishwasher using Dishwasher Magic, Lemi-Clean, Lime-A-Way, CLR, or vinegar until scale is removed from the machine, then add a rinse aid to the dispenser, which should prevent future problems. For very hard water, regular, periodic descaling treatments should be done. For the vinegar cleaning, place a full cup (8 oz) of vinegar in the top rack of the dishwasher. This way the vinegar is release throughout the wash cycles, performing a more thorough cleaning.

1. Over the past 2 weeks, my cups have a sand like substance in them. I have hand washed every item before loading and even changed brand of dishwashing detergent. I then took out the screen in the bottom and cleaning it. It is still happening...help!
   Dishwasher not cleaning

you have scaling problem , your water is hard and you need salt to avoid scale build ups, and gleams on the dishes. you have to determine first your hardness level in your locality, once you have your hardness level, set or program your machine to that level by pressing the command button, see the manual,there is an instruction how to preset your machine for water hardness level., the led light will blink according to the hardness level you choosed, for example it blinks 4 times it is preset to hardness level 4, if the hardness level on your place is at that level it should be your setting,after that turn off the main switch, your machine is ready.note:use only dishwashing salt not culinary salt.