Indesit washing machine smelly water in the drum

My daughter has inherited Indesit IWC71452 washing machine in her flat which appears to be working, washes the clothes okay but she keeps finding a pool of water in the drum afterwards which smells bad. We've tried the following

Taken out and cleaned the filter - smells disgusting but nothing blocking it and it seems to be clear inside

Ran a hot service wash

It's plumbed into the kitchen sink, checked the U bend which was clean and water seems to be draining fine from the machine.

The conditioner drawer collects water also despite being cleaned

If anyone can offer any further things to try before calling and engineer or buying a new machine we would be very grateful.

Thanks