We just finished cooking a turkey in the Salton Mmodel RS 1279 portable roaster oven. It did a great job and was fast. There is now a whitish stain on the enamel liner which doesn't seem to want to wash off, where the liquid from the cooking process was.located We've tried Baking Soda, but the stain is still there.What would you suggest to clean this off without harming the finish on the liner?