How do you level your turntable?

I use a bubble level on the plinth, not the platter.

Pied,
I use the plinth because that's what the arm is mounted on, not the platter. Might not be the right train of thought, but it makes sense to me to level the surface that the arm is on. Example, say the platter is different from the plinth by a degree. Well, if you level the platter, now the plinth is off, and so is the arm. This could cause the arm to want to swing because it's off.