I have a 4 weight rod that the previous owner (and builder) had broken about a foot below the stripping guide. He made a repair about 8 inches long, using a piece of old rod inside, wrapped all the way with thread. Near one end of the repair, there are 2 cracks all the way around the circumference of the blank. There’s also one similar crack near the other end. I can feel the cracks with my thumbnail on the surface of the polymer, but I can’t tell if they extend into the blank itself. I don’t trust this rod, and no doubt, neither does the builder, since he gave it to me for free. I’m just going to maybe re-use its components some day. I believe this rod was built on an early Winston blank.
I don’t know the repair details on this rod, so I can’t say why this one failed. There may have been a problem with the adhesive used, or perhaps surfaces were not cleaned with isopropanol before gluing (absolutely imperative on any glue repair, in my opinion), or maybe there was a problem with the plug, or something else.
Just one experience to add to this interesting discussion.