How much of an ass pain is it to change out tuners? I've currently got a set of 3+3 Grover Rotomatic Tuners 18:1 on my guitar. If I wanted to swap these out for some locking tuners is that going to be something I want a shop to do for me or can I just pop in a set of Locking Grover tuners without doing to much surgery on the headstock. I don't mind a little woodwork but I don't want to be some cockmonkey and F^%$ up my guitar.