Place Leveling Device at center of head cushion and place the cue ball on top of it. Let the ball roll naturally from the leveler and mark where the ball stops.
Do the same from the center of the foot cushion and mark where that ball stops. If both marks are the exact distances from the 2 cuhions from where they rolled, the table is level from end to end.
That's great! But, for instance, if the ball that rolled from the head cushion ended up 2 or 3 inches farther from from the head cushion
than the ball that was rolled from the foot cushion, the table is high on the head end and will need adjusted accordingly.
(Reminder: Hold the leveler firmly against the rail and the table top by placing
finger on top of back. Make certain the leveler does not tilt or move
as the ball rolls from it)