Regardless of how look at it, it's what you hear that matters.
Making your armtube or cartridge perfectly level is pointless. Marakanetz's advice was useful, being specific to your cartridge, but even the ideal visual indicator (SRA measurement) only gives you a rough starting point. Obsessing over it is a waste of time. Ultimately you must use your ears - unless you bought that Titan-i to look at more than to listen to! ;-)