The shaft log tube is made of fiberglass. I used a small diameter rasp and then a drum sander on my drill to hollow it out a bit. I used a spade bit extension shaft to make it long enough to get inside the tube. I don't recall the wall thickness, I think it might have been around 1/4", but it was enough to let me feel comfortable in removing a bit of material from the inside wall of the tube. I also passed a rag smeared with epoxy through the tube afterwards to seal the surface that I filed away.
I had a bit of trouble with the prop strut, it was out of alignment with the shaft log tube and I could not get the new shaft to line up and go into the opening. This was not apparent with the 3/4 diameter shaft (but may well have contributed to the vibration we were experiencing). With the help of my mechanic friend, we removed the cutlass bearing, and used an old thick prop shaft to lever the strut into proper alignment. This was tricky, but worked.
You can email me at roulton@smss.com if you want to discuss further directly.
