Find a steel rod app. 1/4 " dia. Put a 1" to 2" slit in one end with a hacksaw. Place a piece of emery paper in the slit. Roll up paper ( grit out ) for hard pressure or place 2 short pieces back to back for light buffing. Place the other end in a electrical drill. Put in seat tube. turn on drill. end of problem. ( you will find this hand made tool good for a bunch of stuff.