I had the same issue and took it to the dealer. According to the paperwork, a technician had to undo the center console side strips to partially remove the carpet in order to gain access to the vent. But, in my case, the tech left a small tear and a scratch on the side strips (leather or vinyl) which the dealer had to fix. Go figure.

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2011 BMW 740i
2011 Toyota Sienna Limited
2008 X5 3.0 Space Gray (sold)