Bosch Exxcel Diswasher not washing properly?

There is only one wash pump but there is a motorised diverter valve in the base which diverts the water alternatively to the wash arms so only one wash arm spins at any one time. It could be this valve is jammed so only top arm is fed, if it is working ok you should hear the arms change every 1 or 2 minutes. You didn't give model no so cant be more specific. Also could be blocked bottom arm or low water level. Cheers

Kenjo
April 2013