Thank you for all your replies and comments! I will post all of the pictures from the luthier. All of this is very surprising to me, and deeply gratifying. Not because of what it might mean in regard to the value of the guitar, but because it has been with me for so long and after the recent work it is a totally different guitar.
I bought it in 1989 from a shop in Boston. My grandfather had recently died and left all the grandchildren a little bit of money. I think I bought it for maybe $650. I was 19 and a freshman in college. I was told it had been owned by a gigging musician at some point, which was the reason for the dual pickups that had been installed. One of them was pretty much hanging out of the guitar and was never really functional. Both pickups were passive, with one that responds better to higher frequencies to compensate for the Guild’s “boomy-ness”. This is all what was told to me at the time, but quite frankly I really didn’t give a shit because it was a very big and cool 6 string, had a functioning pickup, sounded great, and, well, I was 19.
That was 34 years ago, and since then there have been many other guitars that have come and gone. This one, however, was always special, even as it slowly declined and became more and more unplayable. This guitar has gone everywhere with me over the past three decades, and where I have taken it and how I got it there would make people on this forum shudder. Just a couple examples: I had a motorcycle in college and would strap this guitar onto the back and go into the white mountains for camping and hiking trips for weeks at a time and in all kinds of weather. Snow, rain, mud … all very common in those days. I also lived in London for a while after college, and got the Guild over there by wrapping the case in bubble wrap, dropping it into a fed ex box and fed ex got it to England faster than I got myself there - it was there waiting for me when I arrived. And I shipped it back home the same way I shipped it over.
But in the past ten 10 years, the guitar had really declined. The action became more and more untenable, the intonation was very bad, and with a couple of newer and very functional Martins in the collection, the Guild sat in the case. I would love to say that during this time I at least paid attention to proper humidification - but you can probably guess the answer to that.
I am now playing in a small band in Massachusetts, and decided to break out the Guild at a recent band practice. Notwithstanding its condition, and it being barely playable at the 10th fret and above, everyone was amazed at the tone, including me. So I decided to see what a very reputable local luthier could do, and the results are nothing short of amazing. It has never played or sounded as it does now. Even when I first bought it, the Guild was never as “playable” as a Martin, which had become my go-to in acoustics over the years. But today, the Guild is hands down the most playable acoustic I own. It has incredible response, an even and smooth action, and there is simply not a single dead spot on the neck. Every note, any note, crystal clear, regardless of where I am on the neck. It is an absolute joy to play, and given my history with this guitar, it is like getting to know an old friend all over again.
The Martins need to get comfortable in their cases, because our gig season heats up in about a week, and F-48 is in the #1 position in my lineup!