Yes, I was giving that some thought. I don't have the tools to cut
the wood. Will lumber yards custom cut pieces for you, especially the
thickness to match?
Boy this job looks like it should replace the wood rather than fill
it.
http://www.youtube.com/watch?v=gWvEY...eature=related
I noticed that some people use wood hardener.

It wasn't damaged by the power washer. It was damaged by rot and
neglect.
The only way to proceed that will last more than a few months is to
replace the timber. *Remember, rot spreads, it could spread into the
structure of the building. The rotted timber needs to be removed, and
the surrounding area treated to kill the spores with an anti-rot
chemical.