I need to clean my kitchen's oven really well. It is electric, has a "grill" element on top, and a fan behind a grating which, apparently, cannot be removed. I tried with the spray products for ovens but I cannot reach every part of it, and I always have the sensation that I'm not cleaning, I'm just detaching oil but even after removing it with paper and cleaning more with alcohol, the oven stays oily anyway.
Do you have any hint on how to clean it as close as brand new, and what are the precautions to keep (if any) in order not to ruin the grill element ?