Hi rachel,If the water is coming out of the spray arms but only slightly,the motor is not circulating properly.If it is both arms then the motor is faulty.The cost of a motor and labour is approx £220.
If it is only the top arm that is faulty and the grey tube that goes from the base to the top arm is loose,then you just need a part called a COVER.It is only approx £15.
Hope this helps. All the best.
Foxy
July 2008