Can you post the model number of the appliance please?
Is the dispenser door opening?
You say you've checked both spray arms and they are working alright.
Are they actually turning when water is being sprayed through them?
Ok, thanks for that.
And what about the dispenser?
Is the machine heating the water?
Are you getting any flashing lights to indicate a fault?
The more you tell me the better the chance of a remote diagnosis.
Sorry, the fault has to be with the spray arms as it these that wash the tablet out of the door.
Check the spray arms again, particularly the end holes.
Get the machine washing.
Open the door.
Set the spray arms at a front to rear position.
Close the door.
Allow to wash for 2 minutes.
Quickly open the door and see if the arms are moving.