Pump Problem with Bosch Washing Machine WFS 4030?

My old Bosch WFS 4030 GB/02 has worked perfectly for 12+ years ... until today. It did one lot of washing OK apart from sounding louder than normal. I put in another load and it started up OK, filled with water, but then stopped with a fault code of 1400 LED on and 900 and 600 LEDs flashing. The drum did not turn and it would not pump out. Played around with it for a while - cleaned out the pump - still would not work, but the fault code had changed to the 600 and 900 LEDs blinking alternately. We first thought that maybe it was the drum motor -this has been taken out and checked. The brushes are fine and the motor looks OK. Put it all back together but still the same problem. The machine seems to be trying to pump - lots of noise, but little to effect and the drum will not turn (maybe because it can't pump properly?). Does anyone know what the fault codes mean for this machine. We would like to repair it if possible.