My miele novotronic w310 has a mouldy smell, I have tried cleaning the folds in the rubber seal, what could it be?

MAIN CONTROL BOARD MIGHT BE PROBLEM

Did you try to set the temperature to the minimum?
Maybe the heating element is faulty....

If lint material has collected around the heating element this will happen. Locate the element and clean out all debris, lint, etc.

You need to wipe the seal down with vinegar. Mold needs water to grow. Have you looked at the bottom of the dishwasher after a cycle to see if you have standing water? While you are looking clean the filter.

go to www. repairclinic.com and buy it

God bless you

mAYBE IT IS RUSTING?

No.
At the beginning of every cycle water enters appliance via top of door seal this is connected to the inlet water supply

the filter is on the bottom left side in the front panel
also the drain pump is there.

if you mostly use lower temperature washes a bacterial mould builds up inside the machine. it can be seen as a black residue in the soap dispenser drawer and in the folds of the rubber door seal. a grey sludge also builds up on the inside of the wash drum and the drain filter. doing at least one hot wash ( above 60 C ) a week can stop this happening.

If burned rubber or insulation you can tell. Burning smell
Just bad odour can be from clogged filter, clean it periodically.

When not regularly cleaned and use on 30 -40 degree celsius, fungus becomes a problem. You can try cleaning the soap box and compartment with ttootbrush (old). And run the machine hot empty. When over the years fungus got everywhere, you need to disaassemble all or buy a new one. Don't try aggresive cleaners.

Also you might have a problem to the waterlock to your sewer. Check hose.