Thanks Keith. Adjustable truss rod. To begin, this is a Sigma, Martin spec D28. I was given this guitar already stripped of hardware. It was damaged with body cracks that I fixed. However the previous owner said he had the fret board sanded and it was pretty darn straight. I had it for over a year while I worked on the body. When I started on the frets there was still some glue and trash that I filed out. Once clean I measured the slots at .020-.025 wide. I also filed a slight edge bevel on each slot. By the time I got around to fretting I notice a slight back bow, very slight. I bought the Stew-Mac, medium (#152) that was supposed to be like martin, for .023 slots, but with the taller fret crown. MANY people said they made this change successfully. I've done fret work before, levelling, crowning, but never installed or pulled. I'm real leery about pulling them - Or more honestly, scared shitless. There was already some fretboard scars from the previous pull.
I'm no expert on the topic, far from it, but I did refret an old Yamaha last year.
It didn't matter much if I made a mess of it so it was a good learning experience but, as it happens, it went really well!
For removal I adjusted the truss so the neck was pulling back, effectively opening the slots a bit.
I went over each fret with an iron and lifted them one by one with a razor blade, going in flat then levering slightly along the length of the fret, so as to lift the fret ends out slightly.
That way if I was going to leave a mark on the fretboard it was going to be the point of the blade under the fret.
Once de-fretted I adjusted the neck to get it perfectly flat and, in my case, did have to sand a little to smooth it out properly.
My understanding is that fitting new frets should be done with a flat neck and they should go in quite easily.
That way the new frets aren't forcing the neck back, or holding it back.
As I said - I'm no pro...If someone wants to correct anything up there I'm more than happy ^.
If you're interested but worried about it get some old second hand piece of crap and refret it for the experience.