While trying to change the grill on my Jenn air slide in range I tried test fitting the 2 burner cartridge from the right side to see how it would work. It doesn't fit due to a brass fitting on the left side of the inserts and the pins used to hold the gas burner in place. Jennair insists I should be able to slide the unit right in, they also say the bottom of the grill unit should come right out. Am I missing something?