Hey folks. I’ve been setting up my own guitars for almost 20 years, all different bridges, scale lengths, etc., but have encountered an issue that I’ve never experienced before. I just picked up an Epiphone Elitist Casino - cool guitar. I put some DR pure nickel 11-50s on it, because I wanted something more mellow and a slightly heavier gauge than I usually use. Here’s the issue I’m having: The D string is slightly flat from about the 3rd fret to the 10th, but comes back in line around the 12th fret. I don’t have the same problem on any of the other strings. It’s only about 2.5 cents flat at the worst point, but I can hear it. My first thought was the nut, but that should have the greatest impact closest to the nut. This is the worst around the 7th-8th fret. Anyone ever had this kind of issue? Any idea what could be causing it?