Get some leather preservative and let it soak for a few days; same with the suede cleaner inside,or use a small wire brush/hard toofbrush.It seems to have maybe Gosport-tube fittings as well as electric earpieces..An electronics guy would be able to check it out,same with the mic.The big connector is `old` style.Sympathetic cleaning and checking ,then look on `ebay` for pricing on similar,if you want to sell.Goggles and mic clean as well. you can get,on ebay, replacement elastic,not `old knicker `stuff..Stretch it over a `head size` ball,or mannequin head....Nice memento...