I am an amateur at replacing the igniter. However on my Jenn Air the unit (both burners) pulls out by pushing it toward the back as I raise the unit up in the back. Once out the igniter is accessable and easily replaced. But I am not sure about your unit, whether it is like mine?
Unfortunately the igniter is expensive and I am about to replace a second one on mine JennAir. I think the repair industry has a racket on replacement parts. My Jenn Air is about 5 years old.