Yes, the button is hidden under the seatback panel, and is directly in line with one of the steel posts. Not only do you have to have fingers of steel to press it, you also may have to really yank on the headrest at the same time. The three examples I've encountered thus far were all seriously rusted in place.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References