Two questions actually.
Shaft broke approximately 8″s above the adaptor.
2. – Do sell shafts with Opti-fit already installed?
I use the above tools also. I have better luck with a butane torch similar to item LPT500. These can be found at most home improvement stores. The problem I have with the heat gun is it discolors the adapter. 10-15 seconds with the butane torch on 3 sides of the adapter and it comes right off and doesn’t jazz up color. Also a good chance you “might” save the ferrule.
I saw this on youtube the other day. Probably the best I’ve seen: https://www.youtube.com/watch?v=w8j5QDDGDjQ
After viewing this video, it will give you an idea if you’re ready to tackle something like this.