Conventional oven sprays contain some of the nastiest chemicals. Many are corrosive lye-based (sodium hydroxide) solutions that are dangerous to inhale.
Our green cleaner put the oven parts into the outside sink (which is larger and deeper then our kitchen sink) and soaked them for several hours. I wish I knew what she put in the water to soak off the grime.
I’ve had lots of success with using bicarb soda and vinegar for cleaning the top of stove and around the hot plates. The only problem was that I accidentally blocked up the gas hole and then one plate didn’t work properly until I gave it another more thorough clean.
Mix bicarb soda with water and leave the paste on for half an hour to loosen the grime, then wipe it off with a sponge or rag.
Karen Logan in ‘Clean House Clean Planet‘ recommends using a putty knife, razor and pumice stone to clean the oven.