broken brush

[Quintero]

Can I simply add some epoxy to that little shelf that previously held the knot, or do I need to drill that out and refill the hole? Many thanks!

 

[Doryferon]

A little work with your Dremel tool and some Epoxy will do the job
Happened to me also,don't worry.

 

[patten1969]

Use marine-grade epoxy. Apply epoxy inside handle, insert knot and twist slowly back and forth to ensure complete coverage/adhesion. Don't use too much epoxy; you may want to wrap knot in paper and tape around hole so epoxy doesn't get on the handle. It's easy!