These are the most common tone hole problems and can be found on brand-new, expensive top model instruments as well as cheap ones.
They can be hard to detect without removing the keys, leaving them often overlooked. Chips will cause leaks resulting in intonation problems, unevenness, bad response, fewer overtones, etc. Chipping can be caused either by the nature of the wood, faults in the production process, transportation, or just through the constant exposure of sound vibrations from playing. When your instrument starts to leak, this could be the first signal.
A damaged tone hole will need to be restored. Once it is the clarinet will play fine again.