glennj
I'm assuming you are talking about the film covered the inside door. If it's damaged by the burned food particles you can not clean it but you can replace it together with door body. Check out the door break down diagram.
By the model number of your microwave it looks to me it is at least 10 years old (you can find the manufacturing date on the name plate on the door frame) and I do not think it is worth any money to invest in it.
You can buy a brand new over the range microwave for about 200 bucks.
Gene.