The only issue I have had with the Ferrule is when it's not a great fit to start. Generally, I take a small cleaning wire brush and run it through it for texture sake, and use acetone to clean the shaft tips up before epoxy ( wipe the residue off for peace of mind) with steel I make sure it gets epoxy inside, on graphite I generally put it on first, pull it down to the head and work it around a little so you get some in there without making a mess of the paint. I have had a few give me trouble with steel long ago, but I just pushed it up, cleaned up the shaft area, put the ferrule back in place, hit it with a hair drier to get it to shrink as much as possible, wait for it to cool and re expoxied it. Never had the issue again.
Come to think of it, he only epoxy failure I ever had was Brampton's too, but it was a long time ago. It did ruin a shaft as the head twisted on impact and shredded it. That sucked.