I was interested in getting a Hamer for a back up to my usual guitar, and for $50 I bought a Korean model sunburst that had the headstock repaired, had no bridge or tailpiece and not tuners. The repair seemed good, but was a little rough and needs some apparent touch up work. I put on the bridge and some new PLanet Waves tuners. The guitar will not stay in tune for the life of me. It will be intonated properly at the open notes and 12th fret harmonic but then be off in other places once I play it for ten seconds or more. I don;t think I have the tuning pegs wrong or that they are slipping. I am looking for some advice on whether or not it could be the repair giving way as the strings tune up. Can this be a normal result of a bad job on the headstock repair? Thanks for the help in advance. Bob M.