Seal on inside of lid

I noticed that there is a type of seal running around the inside perimeter of the casing. So when the outer casing slides down onto the main unit, I assume this seal is either to create a cushion for the casing to sit on or its to seal one area of the main unit from another area. Anyway, last time I removed the outer casing, some of this seal was hanging off the casing and was quite brittle and several sections of it came off. Can this be replaced?