Try using the pre wash cycle
If your dishes are left in the machine for a long period of time before the cycle starts then food deposits will dry and stick to them.
If you have only partially loaded the machine and not starting the cycle immediately then select the pre rinse cycle and switch the dishwasher on. This is a cold pre wash for items that are stored in your dishwasher until you are ready to put the machine on to a full cycle.
Always disconnect your appliance from the mains before you start examining it!
