I have serious doubts that there was really an issue with the original tube. I think the tube was squished a little bit while in the pot. I have had the exact same problems. I have been checking the tubes before and after. I can get my bushings to fit no problem in the tubes, then I cast them and the bushings will not fit. I have to file and file and file and eventually they fit. While John is a really nice guy and will make you a new blank, I am not going to be able to offer the same service unless you do absolutely everything possible to make the pen work first. The situation is happening to me 90% of the time, so if I replace a tube cast, I'll probably be replacing it for the rest of my life. I barrel trimmed the autumn blanks. They still have to be chamfered and filed inside. There can be a bit of paint in there, and the tubes are tight from the pressure, so they need a good filing. Once you get the tubes filed down enough that the bushings will fit..and they could be a tight fit..spray a bit of cooking oil inside the tubes, then push the bushings in. My blanks won't just break if the fit is a little tight..a lot tight perhaps they will, but not if it's just a little tight. The bushings will heat up and expand the tubes a bit while spinning on the lathe, and the oil will help the bushings come out of the tube. You can finish the pen, and then prior to assembly, the oil in the tubes can be removed with soapy water. I have had this problem with John's blanks, Dawns snake skins and Gary's Carbon Fiber pens. When you purchase a tube cast blank, be prepared to work inside the tubes. Consider it your prep work time, for not having to make whatever is on the tube and the corking, casting and cutting of the blank. Tube casting is a nasty business. If the parts end up a bit loose when you are all done..a tiny bit of 5 min epoxy will fix it. Everyone I ever sold one of these too had to work the inside of the tubes, and not one person broke their pen, they only had success. And I know..I am not at question in this post, but could easily have been or could be down the road. The tight tubes are just the nature of the beast.