Pictures, cause people like pictures...
Gotoh 510 standard 18:1
Gotoh Luxury Engraved 510 21:1
Schaller M6
Schaller M6 top locking back view
Schaller M6 top locking top view...
I've switched between Gotohs 510s and Schaller M6s, for both aesthetic reasons and for different tuning ratio, 21:1 on the Gotoh 510, and cannot hear a difference. I personally love M6 tuners. I have them on a PRS and 3 Zemaitis guitars. You sure you got genuine M6 tuners, I've never heard of sharp buttons.