Because of the sheer size and scale of the assembled NASA/ESA/CSA Webb telescope, some of the equipment typically used to test spacecraft simply doesn’t measure up. One of those is a ‘shaker table’, used to shake spacecraft such as Webb, to make sure they can withstand the vibrations of a rocket launch. See https://www.nasa.gov/feature/goddard/2017/nasa-gives-the-webb-telescope-a-shakedown
