I hate to throw away wood. I would fill in with a contrasting material of a darker color. Metalic powers with thin CA. Put the powder in the hole first, pat it down, and add the CA next to it so it wicks into the powder instead of floating the powder out of the hole and all over the pen. Do not use accelerator!!!!!!, it will bubble and turn white !!! Cover the intire blank with CA to help with any other soft spots. You can always turn the blank down to the tube if you don't like how it looks when finished. Only thing lost is a little time, but you will have gained some knowledge along the way. Here is a Cypress blank I was working on when the knot came apart. I filled it with metalic powder and saved the blank. Jim S