This oven is quite old (i estimate 50+ years), it's been very dirty for as long as i can remember. This one gave me a lot of trouble, especially the glass, but i don't think it's possible to remove the stains any further with only baking soda, water and scrubbing. After a total of 29 hours, about 5 of those being scrubbing and cleaning, and a half kilo bag of baking soda, i feel like it's much better than before, especially with the big stain in the middle gone.