The upper joint of the woodwind instrument is particularly vulnerable to the risk of cracking. The high humidity and higher temperatures that arise when playing are responsible for this. Very often, these cracks go in or through tone holes which can lead to leaks, poor response, intonation problems and unreliability.
In most cases, these problems can be resolved as long as they are properly repaired. The torn tone holes must be replaced with plastic tone holes. Correctly repaired, no sound or intonation problems, or deterioration in value should be found.
In rare cases, the cracks are so bad that they go into the bore. In these cases, a new top joint could be considered. The production accuracy is so good these days that it can be done without risk. We always try to have appropriate spare parts in stock in order to be able to avoid extremely long delivery times.
Just like new instruments, new top pieces have to be broken in properly. If you play them without the correct break-in procedure, they will crack as well - guaranteed!
Cracks should never be pinned. This is an outdated and harmful approach that does more harm than good.