Keep in mind that the tuning method described in the mods and maintenance guides applies only to yoyos with a removable hex bolt and nut axle. Also tightening does not imply that you tighten it if you feel more vibe. The tuning involves rotating the axle or nut one notch at a time and seeing if it makes a difference. Continued tightening as I read your comment above will result in a stripped axle thread.