What would cause my almost 20 year old Caloric oven to not self clean. I set the dials and oven lock per instructions. The oven works, but does not get hot enuf. The safety lock remains engaged for a while after the cycle completes. But, the oven is not clean. I was thinking the igniter, but as far as I can tell, both the oven and broiler setting appear to work properly in normal use.