OK so I'm fairly sure that the nut on my bitsa needs to be opened slightly as even the slightist movement on the trem result on it going out of tune, but I have never touched a nut ( I said stop laughing) because of the problems that come come with it, but I think that a slight opening of it would work.
Now comes the question!
I don't want to spend a fortune on the files, what can you guys (and gal) recommend please?