I have a vintage A2Z with the original tuners. I notice that when I tune by the time I've gone through all the courses some have gone sharp 2-4 cents. I'm used to things going flat as strings stretch but sharp is another story. Sometimes I can hear it happening in real time as if the string is "missing" the correct tension and jumping from slightly flat to slightly sharp.
I will be having the tuners replaced with Rubners and I suspect this will help but I'm still curious what causes this to happen. Can a sticky nut slot do this? Natural expansion/contraction of the top?
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