Please, check if you Oi Bell has been correctly installed. It should not be too tight and not touching handle grips. Use the installation guide in the manual.
Oi Luxe manual is found here
Oi Classic manual is found here
If your bell has had a knock or a fall, you can also try massaging the top section of the bell to reset the small springs underneath.
If poor sound persists, you can fill out our warranty claim form here, and we can troubleshoot further or look at providing a replacement.