Let's start at the beginning. The action is the highest I've ever seen on a real guitar.
I was stymied. There was no reason for this to be happening! I've taken the necks off a dozen other guitars, mostly Japanese dreadnaughts from the 70's and the odd Harmony. This instrument was definitely put together with hide glue. What was the issue?
Something jogged my memory and I went searching through my archives. I found a reference to a specific group of Gibsons in an old issue of the Guild of American Luthiers journal....
Suspicions confirmed -but it wasn't so easy. I cut the fingerboard extension off and revealed an unsullied soundboard surface. A little excavating revealed the dovetail pocket. I had access to the cavity and steamed it for the fourth time. Still no luck. It refused to come free. If you look closely at the pocket above, you'll see that it was cut using multiple passes from a table-saw blade. (What a laborious way to do things - imagine being that guy who had to stand there dragging the same chunk of wood over the blade 15 times...) This was not a fancy guitar. It was put together with haste. Its original price of $9 was roughly a quarter of the cost of a similarly appointed "official" Gibson. That included a case and a harmonica. If you look closely at the top of the dovetail cavity you'll see it's really chewed up. The fibers have been squashed.
This thing was literally hammered together. There was no neck "angle" originally. The neck and body were in one plane. No time was spent finessing the attachment. In engineering terms it's what might be called an "interference fit". The angles weren't quite identical, and with the addition of some glue to swell the wood - there was no way it was ever coming apart. I figured this out when a hairline crack started to appear on the heel surface. That did it. Out came the finest Japanese flush-cutting saw, and I cut the neck free, leaving the dovetail in situ. I cleaned it out using a chisel.
(Sorry I didn't take a photo of the sawing. At that point I was a little exasperrated!)
There was also a lot of finish touch-up. The steam softened things a little in various areas. I used shellac and french-polished it along with alcohol dyes. The effect is okay. It's hard to know when to stop. This wasn't a refinishing project, after all.
What an experience.