So I'm completely geeked out with my new hobby today. I'm working on trying to restore one of my dads old Century handles. I was wondering if anyone could pass along some drilling techniques. I've gotten a good deal of the glue out of the bristle hole however what remains seems to be really hard, like graphite, and my drill isn't making any more headway. This is a brush well over 60 years old and I'm terrified of damaging it.