Set up the lathe on a level surface with no inclines.
Stand in front of the lathe and set a level on the far right-hand side of the lathe top. Make a mental note of where the bubble in the center of the level falls
Stand facing the side of the lathe on the right-hand side and place the level so that it faces the same direction of the side legs.
Have your assistant lift up the right-hand side of the lathe while you adjust the threaded stand feet. Adjust both the front and rear right feet until the bubble falls in the center of the level.
Stand in front of the lathe and set a level on the far left-hand side of the lathe top. Stand facing the side of the lathe on the left-hand side and place the level so that it faces the same direction of the side legs.
Have your assistant lift up on the left-hand side of the lathe while you adjust the threaded stand feet.