Hey guys. I have a Cort SFX1F NS - the NS is the color I think.

Anyhow, it was professionally setup. Great guitar, love it. The action is a bit higher than I'd like though and I changed the strings and got a fret buzz, only on my G string.

OK, I said, low tension because I just replaced the strings, let's take it to the professional. He adjusted the truss rod tighter and raised the action. Later on after the strings wore in, the action got way too high, so I loosened the rod back up. And kept loosening.

The action could be almost literally half the height if not for this G string. The low E had a slight buzz when it was WAY tighter but it went away real fast. The neck is in great shape. The buzz seems to be on or about the 5th fret; it is bad enough to warrant releasing the tension until it is completely clear. Even only moderate strumming would cause it to buzz.

So I have this one problem string. Could it be something I did wrong replacing it? Should I check and see if the associated fret is coming loose in some way? I mean, what things should I look for? Maybe I could file down that fret just a TINY bit and get amazingly low action?

I measured it by the old capo the first, fret the 14th, check height at the sixth fret. It's seriously lower than any other string. The intonation is fine though.

:-\ any advice appreciated
You should also check the bridge, too. The groove for the bridge may have been filed lower than it should've been