Hi there, I bought a PRS SE Custom 24 in august and I never noticed any tuning problem until I changed the original nut with a Graphtech Tusq and the strings from 9-42 to 10-46. Then I began having the G string go sharp in a matter of seconds. I brought the guitar to my luthier and he did a full setup, checking the Tusq, restringing the guitar, adjusting the bridge and so on. In the beginning the problem seemed solved, but it wasn't . I brought back the guitar to my luthier and he re-did the setup from scratch, but the problem was still there. He is a guy who knows what is doing, and is highly respected and even famous around here, so I trust him 100%. He says its' NOT the nut, not the strings, not the neck. He says 60% chance it's the tuning keys, 30% chance it's the bridge. I checked online and the cheapest locking tuners I can find are the Grover 406c Rotomatic. Anyone here with the same issue as me? How did you solved it? I'd like to be sure before spending money on something that won't fix the problem. Thanks!