Cracks

Since the appearance of cracks in bamboo are commonplace, I wanted to post this response on the topic to a letter from someone new to the instrument in the hopes that it presents a slightly different perspective to others who think they are presented with misfortune when this occurs.

...a hairline crack running through the thumb hole.

" Cracks are a condition of humanity.  They are in a large part what makes things unique.  If there were no cracks, we would all be exactly the same person.  The co-relate you found in this aspect to your instruments is no coincidence.  Embrace these little adjustments, for that is what they are.  Your instruments adjusting to their environment.  Interject your care and mindfulness and a symbiotic relationship will grow.
My main 1.8 is an excellent point in example.  It was made for me by my sensei's father, a master craftsman.  He had the bamboo sitting in his workshop for 30 years waiting for the right situation to coax a top level shakuhachi out of it.  I was honoured to receive it from him.  For the first few years that I had it, I was never satisfied with the sound I was achieving from it.  I guessed that it was my inability to produce a good sound.  On one trip back to Canada in the winter, I took the instrument out of its case only to find that it had several long cracks right through to the bore.  It was unplayable.  I was heartbroken.  On return to Japan, I presented it to my sensei explaining how it happened and hoping that it could be revived   He looked at it and laughed (half out of shock and half out of recognition of the unforeseen twists that life often takes.)  He took it and gave it back to his father who returned it to me a few weeks later beautifully bound and playing better than it had ever played before.  I think that being exposed to an inhospitable climate in the winter of Canada relaxed some stresses that were inherent in the bamboo from its growth and certainly this instrument now has a wonderful, relaxed and contemplative tone.  I'm convinced that it offered me a chance to grow with it.
Do take heart.  All cracks offer the potential for growth and a slight change in direction.  Embrace that and use your good sense to move."