Bosch SGS45E02GB/45 partially fills then empties?

Hi,
The dishwasher partially fills and then partially empties in a never endin cycle. I checked the control module and all solder joints looked as new. I've just replaced the flow rate meter (from another suggestion) and have exactly the same symptoms as before. The water level inside the machine is just below the coarse food filter (i.e. it looks empty) and not just below the salt filler cap. The LED display does not countdown. For some reason, on Economy the LED displays 199 minutes (and should be circa 156) but on Auto it is correct at 130. It is also correct on Quickwash and Pre-Rinse. The water matrix and pressure chamber areas look clean. Water is flowing into the machine from the hose at bottom right of the float valve. There is no sign of water backing up and thus indicating a blockage. I wonder if anyone has any further ideas? (At least the flow meter was only £13.)