Problem with kenwood dishwasher?

Hi, Hope someone can help me. I have a Kenwood dishwasher. It has never worked very well, but now hardly working at all. I have checked several things with it and have discovered that the bottom arm is not turning. The top one appears to be. Also the water on an economy cycle is only just above body temp. I clean it regularly, use separate salt, detergent and rinse aid. I have checked that the arma re not blocked and have run a very hot long cycle with soda crystals. Still no luck. Any suggestions?