For the grates, use Easy -Off Oven Cleaner. I would suggest the one in the blue can because it is odorless and it wont burn your skin if you happen to get it on it. Spray them really good,and leave it over night. Then use very hot water to spray it off next day. I usually let them soak in the sink full of hot water and a little 409 next day. For the top of your stove, sorry to say without having it re-glazed, the scratches are there for good. But you can make them allot less noticeable with the use of Lemon Oil. My stove is fifty years old,is black, and has grates that are hard to clean also,but I use the lemon oil after I wash it with a soft cloth and it just gleams like it was spanking new!