My NK65 wobbles
With the NK65 there can be some slight wobbling with the board, however there is usually a pretty easy fix:
Place the NK65 on a flat surface. Remove the six screws in the plate that attach to the bottom of the case. Make sure the bottom case is now flat on the surface by applying pressure to the case to straighten it out. Gently screw the screws back in while keeping the case pressed flat, and it should straighten out any issues. Do not over-tighten the screws as you can strip them if over tightened
A slight wobble can occur depending on the surface you are using. Adding a desk pad underneath will usually eliminate this.