Many people are not aware why their guitars may become harder to play as time progresses. One of the typical reasons is that the stresses over time cause the body to move and the neck angle to pull up. This is often fixed temporarily by lowering the saddle height, but this is not the cure as it decreases tone and string break angle behind the saddle.
Resetting the neck is a major repair job which few repair people perform. It is the one job that manufacturers only trust to the top people in the field. The reset photos above are from a warranty job I performed for C.F. Martin as I am a warranty and service center for them. These photos show the heating blanket and the steaming process. I will be posting detailed articles soon on my website of jobs like this and others.
The process requires the 15th fret to be pulled and a small hole drilled through the fret slot into the air gap in the dovetail joint. The fingerboard extension is then warmed with a heating blanket and gently loosened from the top with a thin spatula or palette knife. Steam is injected into the hole to soften the glue inside the joint. The neck is removed, the heel is slightly carved back at an angle and the neck is re-glued into the body at the new correct angle. This improves action, tone, volume, and intonation. NEVER let anyone shave the bridge lower to fix your problems, as this is a crude value destroying technique only to be used on inexpensive instruments!
All the best, Scott