Woojer Series 3 devices shouldn't rattle, however, if the audio input is too strong - this can happen. This is most likely to happen if your Woojer is connected to the source device through a wired connection.
In this case, we recommend lowering the haptic feedback levels of the Woojer by one or two steps, which will make the experience more pleasant for longer uses.
If the problem persists, please contact our support team.