Gentlemen and Ladies,
I have improperly identified a Guild M 20 dove tail joint as a mortise/tenon joint. After getting a good week's sleep on what I initially said was a mortise/tenon, I determined this morning the joint was indeed a dovetail joint, applied steam, pressure, cussing, etc., and the neck came off.... to reveal the tightest dovetail I've come across. My thanks for all of you who responded to my cry for help, and my apologies to all for the misdiagnosis. (but hey, nobody died here, so I don't feel THAT bad). Next time I chime in, I'll wait for the frustating feelings of a repair gone wrong to recede before I start a discussion. Again thanks for all the support/ suggestions.