Yeah, this one's common. The glass silencer isn't seated correctly on top of the nebuliser. That piece is there to dampen the operating sound.
To fix it:
- Carefully remove the top cone by twisting and pulling it.
- Check the glass silencer (the small insert) is placed firmly into the top of the glass nebuliser.
- Make sure the glass nebuliser itself is fully inserted into the base of the unit.
- Place the top cone back on securely.
If that didn't work: Oil might have gotten into the centre tube of the nebuliser when filling, which can cause irregular operation. You'll need to clean the nebuliser with soapy water, rinse thoroughly, let it dry completely, and refill it carefully at a 45-degree angle.