Regardless of what is printed in the 1999 Owner's Manual (as mine is a 1999 also) or what is in the Shop Manual, MY headrests were NOT removable. I've read several threads about some that can be removed - IF you have the release buttons OR IF you press harder than you expected. Well, after wrestling with my headrest, I got it in my head to tear it apart until I could get them removed. Here is what it looks like after the leather is removed:
I did tear the foam a little because of some "hidden" double-sided tape between it and the frame. Once the foam is folded up and out of the way, I found the headrest shafts had plastic inserts inside the seat. Well, the lower part of that plastic insert has tabs that hold them down:
And the upper part has a similar part that keeps the entire plastic assembly from rotating (as that would release the headrests and assembly):
So the bottom tabs were removed here:
And here
The top part of this assembly acts as an umbrella preventing you from reaching the parts that would allow the top parts to be removed and release the headrest only:
Here is how the pieces line up (note the leather would normally be located on the black mushroom cap on the ribs near the top). Notice this pic shows the metal clip that had the all important metal clip that has the unbreakable metal retaining pin:
Note the other side of the clip is open and rounded for easy removal:
Also note how large the metal pin is. There is probably no overpowering that thing.
Here you can see that last indentation has a flat bottom that prevents the headrest from raising any higher or being released:
Hence, these are the parts that I removed before re-assembly:
This is the new assembly setup
Wiggled everything back together and the headrest is now removable and still adjustable. Mine are still pretty stiff to raise and lower, but even if they were loose you could "modify' the plastic assembly or even the metal shaft to create more friction.
Now that I have the seat assembly taken care of, I'll start researching the coveted heating elements (or perhaps a new seat cover), etc...
Hope this clarifies why some people can't seem to get the dang thing to release.
Sam