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The lumbar support is an inflatable bag behind the seat cusion and leather. My guess, since you're hearing the motor, is that either a plastic tube that provides air to the bag has become disconnected or there is a physical cut/break somewhere in the bag or tube. Here's a picture where you can see the bag (or bladder, or who knows what it's called): .
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.