You might need to reset the toothbrush. If it is on the Easy-Start feature, you will have to deactivate it.

• If your toothbrush is in Easy-Start mode, you will hear 2 beeps immediately after turning on your Sonicare (it is easier to hear the beeps if the brush head is attached). 
• To deactivate the Easy-Start feature, attach your brush head to the handle and place the handle in the charger with the charger plugged in. Then press and hold the power button for 5 seconds. You will hear 1 beep to indicate that the Easy-Start feature has been deactivated. 
• If the vibration is still weak, contact customer service.