Miele CVA 7840 Operating And Installation Instructions page 15

For machines with stainless steel surfaces:
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Do not use sticky notes, transparent adhesive tape, masking tape
or other types of adhesive on the stainless steel surfaces. These will
damage the stainless steel surfaces, causing them to lose their dirt-
repellent protective coating.
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The finish on stainless steel surfaces is susceptible to scratching.
Even magnets can cause scratching.
Warning and Safety instructions
15