Bosch dishwasher rotor arm not turning?

I have an intergrated Bosch dishwasher model no. SHV43A03GB/44. The top rotor arm does not turn. I have had two different engineers look at it, the first suggested it was the pressure chamber assembly which needed changing, when this did not work they said the machine was beyond repair. I then found another engineer willing to look at the machine and he diagnosed it was the impeller kit which needed changing. The seal had broken down and was about to let water into the motor. This also has not worked and again the machine is standing still. The second engineer is willing to call back again to look at the machine if I can find out any information for him.
As a result of surgery I have a weak arm and as such a working dishwasher is very important to me, so I would really appreciate your help.
Thank you.