fixin gas caps

i bought a gas cap .....it is a cuda flip top cap .....well the gasket is in very poor shape .....(not complaining i got it from a member for cheap and i knew what i was getting)

so now that its here ...is there any way to replace the gasket or make it seal better ...the gasket is original and cracked. has anyone repaired these?

if i cant fix it it will become wall art but if i can fix it then it will be painted and go on my dart :glasses7: