In addition to the informaton that you already received, hereĀ is a Q&A I wrote back in 1998 that might help.
Question:I have some minor repairs that need to be done.Can I use an unlicensed handym ... read more
There could be infection spreading under the bark. Sooty Canker is one possibilty, black powdery fingus spreading under the bark. Have an arborist look at it. May be able to remove infect branches, tr ... read more