Well Doug,
That is interesting. The glue you have been using is good stuff but I would suggest using Titebond wood glue. It is much better. I started many years ago using Elmer's wood glue. It did good but today's glues are so much better.
Now for part two of your question on the resetting the neck:
If the glue job holds well and you decide to stay with the present neck then I suggest very carefully using a needle and very hot water to begin opening the glue seam. It is a slow process. Once you have melted the glue loose then you have to wiggle the neck around and back and forth until you get it loose enough to come out just like a dentist pulling a tooth. You can make a wood shim sloping from front to back thinning at the edge as thin as paper and get thicker toward the other edge. Glue the shim to the bottom of the neck block and then reglue the neck into position. That will be a good solid glue joint again as well as provide the new angle you need. Of course you are looking at a refinish job too.
Rick Andrews, Andrews Guitar