This answer is for firebrick kilns with sidewall elements. It does not apply to ceramic fiber kilns. (You will see heating element grooves and brick seams inside a firebrick kiln. Most ceramic fiber kilns have embedded elements that do not use grooves.)
If your kiln is new or you have just installed a new element, perform the “Kitchen Knife Test.” Do not perform this test if the element has been fired. Always unplug the kiln before touching an element with anything.
THE KITCHEN KNIFE TEST: FIREBRICK KILNS WITH SIDEWALL ELEMENTS
Press the elements into their grooves by running a blunt kitchen knife, plastic comb, or similar blunt object completely around each groove. Do this before the first firing, because it may not be evident to the eye whether the coil is in its groove. If the element doesn’t lie flat in the bottom of its groove, you needn’t be concerned as long as the element fits all the way back into each corner and doesn’t bulge outside the groove.
FIRING THE KILN TO CONE 05
When the kiln is fired to cone 05 or hotter (1888 degrees F or hotter), the elements soften to the point where they no longer support their own weight. If they are inside the grooves, they will conform to the shape of the grooves. Occasionally firing to cone 05 or hotter will help prevent the elements from bulging out of the grooves.