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Describe whether only particular utensils are affected and whether crockery has marks too. Include a product change or mixed metal items in the load.
Keep a repair enquiry proportionate
Photographs and programme details can help decide whether an appliance assessment is warranted. Do not assume the heater or tub needs replacing solely from a stain on cutlery.
A useful distinction
A removable surface deposit and permanent pitting can look alike at first glance. Preserve the distinction as uncertainty rather than asserting that the machine is corroding or that every affected utensil is damaged.