Whirlpool DWF 416 dishwasher (Ikea) not washing properly?

Machine is not washing properly

The machine does not seem to fill properly – you can hear the pump cavitating during the wash cycle. If I add a pan of water during the wash cycle, the pump stops cavitating and all sounds fine.

The fill valve is part of the assembly that attaches to the tap – I have had this apart, cleaned the filter, etc.

What sensor detects the water level and stops the machine filling? Or is this a pressure sensor. Is any adjustment possible? I presume it can’t be a simple timed fill as the fill volume would vary depending on the water pressure – which will be different across the country.

Many thanks for any comments.

With regards

Colin