Ok, had some down time yesterday due to the "ice storm" and did some work on the brush. I first tried soaking the handle in hot water for a while and was surprised that the marine epoxy I had used earlier got soft. After about an hour in and out of hot water I took a drill and bit and drilled out most of the old original glue and grounded down the bottom of the knot. Lost a few bristles in the process. Here are some pics.
Here is what it looked like before the grinding and drilling.
Attachment 154627
Bottom of the knot after grinding. You can start to see the bottom of the bristles.
Attachment 154628
Here is the handle after drilling. I had to go down 7/8" before hitting the wooden base. All the material I removed up to that point was all original glue. Made a bit of a mess with the metal ferrule though. Most of it was on the inside.
Attachment 154629
Attachment 154630
Here is the knot sitting on the handle after all the grinding and drilling. It won't go any deeper because the metal ferrule tappers in and matches the tapper on the knot. I guess the next step is to figure out how to fill up the void in the handle and what to fill it with.
Attachment 154633