If there are large chips gone, pretty much cutting in a patch is the only option. The problem is wood match. This is my first effort at repair here:
Grip repair
Since posting the after pics here and elsewhere, several folks have suggested trying to match the grain with an artists brush and stain. A friend that does museum restorations suggested that even now after finishing, I could use thinned artists oils to put a better match on the grain.
The factory finish is Polyurethane and most recommendations to me were to use the wipe on type. Zip Strip took the old finish off no problem.