I bought this four years ago for my daughter, but she only used it about 8 times a year on days when she needed a packed lunch, so the packing and seals are still in good condition. The lunch wrapper has one large stain. It hasn't soaked through to the other side. Would this be something someone good at stain removal could fix? Also, the lunchbox is barely used, so it requires a fair amount of force to close, and even more to open.