As Stefany says, applying too much pressure may fracture the bead.

I have used this method especially when the knot is glued or has otherwise become very rigid. The bit has to be very sharp and essentially you are cutting the knot material away gradually.

The pin vise is an inexpensive hand tool that is readily available. I bought several solid carbide, brad point twist drill bits in small sizes for my tool kit and these have worked well for knot removal. The bits are made by ultratool and I buy from McMaster-Carr. They are about $15 each. Very sharp!