g slot pinching the string

Hey guys
I've got a wee problem at the moment. What I think is happening is the G nut slot is too tight and is pinching the strings. I'll be tuning up and not much will happen and then it will go 'PING!' and jump up half a semitone or so. and same when I'm going down, you'll release the tension but it'll take a couple of winds until it releases doing the same 'PING!' thing. I notice that with strings like elixirs the G string seems to be under a whole lot more tension and it's really bad with these. difficult as to tune because it wont slide up it will just jump. any suggestions? should I just widen the nut slot? and also should I be buying a lighter gauge of string? I just use normal 12's
thanks heaps!

if you have any old strings still such as a "D" string, you can use it to slightly widen the G slot (like floss). Still, how did it get this way? Since it happens whether tuning up or down, I think you are right about the overall width of the slot. I would say, as a test, use the lighter/narrower gauge next time and see what happens.

Greg

I dunno a, I took it to get set up ages ago and I think it did it a little bit after that. I normally just use martin sp's and it doesn't do it real bad with those, I probably just could never be bothered taking it back to get checked but now it's starting to do it real bad. thanks for the help though, I'll see what I can do