I thought I had answered this, but maybe the reply didn't post... Vent cap? Could you be more specific about what you tried and what the noise is like - where it seems to be coming from? It looks like on some of these models, the high-voltage section emits some interference which some people are blocking with a foil or metal shield. If they do that, they should definitely insulate it to prevent shorts. Another cause of vibration on these models is a fault in the stirrer located above the cover on the ceiling inside the cooking cavity. Feel free to post back so we can help further.
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