Harry, just an FYI, I just read a book where it talked a bit about graft incompatibility and it said that if after many years of normal growth, the tree breaks at the graft union, it would be a sign of delayed graft incompatibility because the cells of the scion and those of the rootstock have never interlocked (as in a compatible graft). Now, Mr. Chance could have played a role here in tandem with Mr. Storm, but I think the book has a good observation here.