Your dishwasher may need to be cleaned. Have you tried wiping out all the crud that accumulates and cleaning the filter? After doing this, run it empty with a cup or two of vinegar in a bowl. Do this a couple times. At the end of the cycle you can see if there is still crud floating around as it will accumulate in the bowl. I think there is a method of doing this with bleach for a more heavy duty cleaning (but not the vinegar and bleach together.) google it. I would try this before throwing your dishwasher away.

Did you note the point about cleaning the filter? New dishwashers don't have food grinders anymore.

Also check the spray arm holes for clogs.