It may be the circulation pump, is not providing sufficient pressure to wash the plates.
When the dishwasher ends, is there any sign of water left in the sump of the dishwasher?
So this suggests the drain pump is working, and I would think your looking at a faulty circulation pump.
Can you send me the model number and I can look to see the cost of replacement pump for you, however would expect it would be rather expensive from previous experience as they often have integrated elements.
Hi David, please let me know if I can be of any further assistance.