Zanussi DWS39 does not drain

Hi, our Zanussi DWS39, Product Number 911734013, Serial number 04380073 is not draining correctly. It goes through the complete cycle but water still remains in the bottom of the dishwasher to a level covering the filters. I have removed and cleaned all the filters- no heavy food deposits present. The Wash pump is working fine- I have checked it anyway for debris and it is OK and the impeller spins OK. I also checked all other tubes and pipes and found no blockages. I checked the drain outlet for debris and this is also clear. The drain hose has also been checked – no blockages or debris in the hose and its position into the drain pipe is OK and is not causing any siphoning back into the appliance. I removed the drain pump and checked that there is no blockage or debris in the pump- that too is clear and the impeller can be rotated easily so no issue there. Using a multi meter I checked the resistance across the connector terminals of the pump alone and it has a reading of 172 Ohms. Having viewed the e-spares info it indicated a good pump should be around 200 Ohms. Would you expect 172 Ohms to be in the OK region indicating the pump is OK or is it too low compared to the 200 Ohms recommended indicating the pump may be NG and in need of replacing. Are there any other diagnostic checks you could recommend to try and get to the root cause of the problem and ultimately a fix. Regards. TPZ