I'd suggest cleaning all the old fiber fill material out of it, and replace it with the spun fiberglass stuffing out of an air conditioner duct filter. Just wear a respirator mask of some sort to avoid inhaling any airborne particles that might get loose while you're re-stuffing the housing. The loose-weave fiberfill packing that's used in upholstery work for pillow stuffing might work OK, too.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!