I have a rocket that I had to replace the shock cord mount - on a previous flight the ejection charge was way too powerful and ripped the mount right out of the tube. I made a replacement, and installed it, flying the rocket today. Unfortunately at ejection the replacement mount gave way and the rocket tumbled to the ground, suffering substantial damage. When I recovered the nosecone + parachute assembly, I was surprised to see that while I had indeed been generous with the glue, that the soot on the inside of the tube kept the glue from bonding with the body tube cardboard.

Is there a good way to clean the inside of the tube well enough to get the glue to stick? How have you guys handled this kind of situation? Thanks.