Owner of 4 Gibson’s here, spanning 1965 to 2020. Plenty more in between I have sold or traded. Your binding issue is a poorly cut nut. I’m guessing excess material on the back side, and/or the top of the nut. The plucking noise is caused from the string catching in the excess nut material! I have never put graphite in my nut slots, or changed the stock tuners on my guitars and I don’t have binding or tuning issues. I even use a bigsby on one and maestro on another and they are rock solid as far as keeping tune! You need to get your nut properly filed by a luthier to remove the excess material, and run some gauged files through your slots to match the strings you want to use. Well worth the $75-$100 it might cost, if you can’t do it yourself.