I am refinishing an old acoustic archtop my grandfather made in the 60's. The wood he used for the neck and the sides appears to be a very light-coloured mahogany. Both the neck and the sides were painted black with god knows what, and he doesn't appear to have filled the grain with anything (he was an amateur luthier and was flying mostly by the seat of his pants as far as the building went).
The result is that the heel on the neck, both sides of the neck, and certain splotches on the sides have been stained quite deeply with the black paint. It appears that no amount of sanding will fix it. I've already sanded so much off of the headstock that I'm going to have to glue a 1/4" vaneer onto the face to keep it a decent thickness, and its still not clean of all the paint. I can't make this same error on the sides or on the heel, it would ruin the guitar.
I used a citrus stripper to get the lion's share of the finish off of the guitar, and it worked pretty well on the rest of the guitar. I tried using an "after strip" cleaner that is supposed to rid the body of the rest of the finish still lingering, but it didn't really do anything. The top and back turned out quite clean after a little sanding, and the neck itself (not the heel or the headstock) is also clean. The problem areas I mentioned won't give up the paint no matter how much chemical stripper I use or how much sanding I do.
I'm going crazy here, this guitar is very important to me and I want it in the best shape it can be. I know I can't start to finish it until all the paint is off, what can I do?