JR calls it a Spindle Shaft. Its the metal shaft that holds the blade grips on the rotor head. With the blades off look inside the grip, you'll see a nut, that nut is threaded onto the spindle shaft. If then heli was brand new chances are its not bent. You can look at the space between the blade grips and the yoke with the blades off you should have an even space all the way around if its not bent. You can also with the blades off just spin the main rotor by hand and look down at the head button and see if it looks like its wobbling. These checks will let you know if there is a real bad bend but if there is only a very slight one you might not be able too see it this way. If you think that either might be bent pull them out and roll them on a smooth surface. Again if like you say this is a band new heli its very unlikely either is bent unless the heli was dropped or damaged in shipping.