Citric acid will clean hard water deposits run several cycles with it

I think I've done it now with a combination of several fillings of caustic soda then rinsing clean water through and shaking vigorously!
I'm going to put it back on the machine and hope it works ok now.
By the way I took the pump out and I found that the rear end of it had water in the casing. I cleaned it all out and pushed it back together. It turns ok when power leads are connected to it. Does this means it's ok? I only ask as the engineer got an intermittent fault code from it.
I suppose I'll find out soon enough when I try the machine.

Success! It all works again the water heats up, the pump pumps out and it goes through the cycle fine although not tried the longer washes yet.
So far so good then, but I'll have to wait and see for a couple of weeks to be sure. I've seen a lot of posts on forums about Bosch dishwashers hanging on 1min and not heating the water etc. The common advice is to check the PCB in the door, but it seems that if the water movement is impeded in the matrix, it can cause the machine to disfunction, so my recommendation would be to clean all the pipework as well.