Bug-grrrr

 The big Yew primitive exploded on the tiller while being exercised at about 80#. I was very surprised as a wide thin limb is much lower stress that an narrow thick one.
Anyway I did a post mortem and found some bug damage in the very thin sapwood, there was also an area where the bark had been chaffed through, presumably by a crossing branch, the sapwood there had that blue staining and was noticeably dryer and less waxy than the rest of the sapwood.
I've inspected the other two staves for any bug holes and they seem ok, fingers

crossed.