Yes. On my TNT the platter is slightly dished, as moving the level around on the platter produces inconsistent level readings. When setting up an arm, you want a consistent reference point-- as provided by the armboard or plinth area close to the arm.
I use a 3" Stanley straight level (Home Depot item). This works better than the round bubble levels that come with most TTs. (1) Place the level on the armboard just in front of the arm pivot. (2) Orient the level from 9 o'clock to 3 o'clock and level the TT plinth from left to right. (3) Orient the level from 12 o'clock to 6 o'clock and level the TT plinth from front to back.
The process takes just two steps, provided that with each adjustment you raise/lower the matching corner towers by equal amounts. It may take a bit longer if you're moving individual balls around.
I use a 3" Stanley straight level (Home Depot item). This works better than the round bubble levels that come with most TTs. (1) Place the level on the armboard just in front of the arm pivot. (2) Orient the level from 9 o'clock to 3 o'clock and level the TT plinth from left to right. (3) Orient the level from 12 o'clock to 6 o'clock and level the TT plinth from front to back.
The process takes just two steps, provided that with each adjustment you raise/lower the matching corner towers by equal amounts. It may take a bit longer if you're moving individual balls around.