Whirlpool ADG6340 IX Pulsing drain and fill cycle 2 seconds

Hi all.

I have a Whirlpool ADG 6340 IX. It started with pulsing on both filling and draining at the beginning of the wash cycle and then again on each drain/fill sequence during the wash.

The drain pump will run continuously during part of the drain cycle and rapidly near-empties the dishwasher, then it returns to the pulsing rhythm again and into a pulsed fill cycle. I’ve checked the drain pump and this is clear and no sign of obstacle or crud.

I’m not getting any flashing LED, I’ve tried running the diagnostic test to get flashing LED but nor sure if I’m doing that bit right.

Now it seems to be overfilling slightly and leaking out the two white overflow pips at the front corners.

The service code is 8511 634 15829

Any advice gratefully received!!
Brian