If you are experiencing issues with the vibration function on your Pebbles, follow these troubleshooting steps:

1. Confirm Session Start in the app: Open the Glimp app and verify that you have correctly initiated a breathing session. The app interface should indicate that a session is active. Make sure the app is running on your phone during your session.
2. Check the vibration intensity setting: In the Glimp app, you can adjust the intensity of the Pebbles by tapping the Bluetooth button on the home screen. Find the “Pebbles intensity” option and adjust it until you are satisfied with the vibrations.
3. Restart the App: Close the Glimp app, then reopen it. Also, shake the Pebbles to 'wake' them up again and see if the issue persists.
4. Check Battery Level: Ensure the Pebbles are sufficiently charged. A low battery can affect functionality.
5. Check if there is a firmware update needed: Open the Glimp app and check for any notifications related to firmware updates. If so, please follow the instructions to update the Pebbles' firmware, and restart the Pebbles and app. Keeping the Pebbles' firmware up to date is crucial for optimal performance. Outdated firmware might lead to functional irregularities, including vibration issues.

If the issue persists, please contact Glimp's customer support for further assistance. We can provide more in-depth troubleshooting or advise on the next steps, possibly including a warranty claim if necessary.

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