Hi Marc,Filling a nut slot that is too deep is pretty standard stuff not only for a guitar tech, but for anyone who is already bent toward DIY-ing. If you already have the proper files, I will presume that you know what you're looking for and are not afraid to work toward that specific goal. Thus, you should simply fill the slot, then re-file to taste. It is less work than replacing a nut then going through the whole process again, IMHO. Read up on it ...pretty straight-forward job Edward