OK, it isn't that vintage but I have a 75 P Bass that has a mild case of fret sprouts. It is a lacquered one piece neck and I am looking for options to running a file down the neck. I just am afraid that I will take some of the finish off of the neck and I do not want to do that. I assume the bass was stored in a dry place for some time. Just wondering if the process could reverse itself naturally. When I used to work in a gtr shop, we would run humidifiers at night and I could actually feel the sprouts retracting on certain guitars from day to day. But this is a finished neck and the sprouts could have been there a long long time..... Any advice or suggestions appreciated!