Miele intermittent drains?

Have a Miele G 1143 SCU dishwasher which I bought used a couple of days ago. It seems to work but sadly not all the way.

When I run the 75C (pots and pans) programme it seems to drain 3-4 times but fails the last drain (does that make sense?) ending with the blinking red light (inlet/drain) instead of going into the last phase (the drying part). When it drains properly I clearly hear it draining normal amounts of water and when it’s not working it still drains water but not the same amounts.

I’ve cleaned and gone through the drain pump and the non-return valve and the machine and all filters are basically as good as new. I’ve also used a couple of cleaning tablets as well as a couple of dishwasher tablets.

Any idea what could be wrong or what I can test?

I’ve speculated in if there might be a blockage in the drain hose which sometimes block and sometimes doesn’t (resulting in intermittent drains) but I don’t know. I’ve also not run enough cycles to be sure that it’s the same drain step which fails or not.

Apart from the drains the machine works good as far as I can see.

TIA!