Try applying the vibration to the key itself while simultaneously applying turning clockwise turning pressure to the key!

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The problem is usually the tumbler pins are not being lifted to the proper height and therefore the tumbler is unable to rotate. Vibrating the key while set the pins to moving and at some point they will all be at or near the proper height and if you are applying a slight clockwise force to the key the tumbler will turn! Higher frequency vibration is better!