May be due to spray arm nozzels blocked by debris. Remove the spray arm & inspect/clean the nozzels & refit. Could also be caused by low pressure from the circulation pump (damaged/worn impellor). To check that the spray arm is rotating at all set it in a certain position by hand (i.e. 12 o'clock pos). Run a wash program & carefullly open the door to check if the spray arm has moved (the door switch will stop the program when you do this).
