A Diplomat Dishwasher?

My Dishwasher diplomat Adp 8322, Brings in water with all relevent buttons on ie, on button in green and a program of 5 green light on either one. after a few seconds of normal noise of taking in water, it then makes a loud brurrrrrrrring noise and doesn't do anything this can go on until i open , when i turn off and on again it will then just drain, I thought it was motor so we replaced with reconditioned one a repair man installed but after 3 days same prob. again and he refuses to do anythink. please help cant afford two repair prices. thanks