Have you tried baking soda and vinegar? It's simple but very easy. Pour and spread baking soda on the parts that need cleaning and then drip vinegar down onto the soda. It'll fizz up and look a little crazy. Let it sit for a while and come back with a soft scrubber. It should come off pretty easily.

i use magic eraser and a bit of water and baking soda on the spots that are hard to clean. I use it for the stove and bath and other things. it always works. The magic eraser removes stains well.