I've got a pretty valuable Sentai/Power Rangers toy (the Muteki Shogun, or JP Shogun Megazord for those wondering) that has a part that is mostly white plastic. When I bought it last August, it was very slightly yellowed (think the difference between United Jazz and RTS Jazz) and hasn't gotten any worse, and I'd like to keep it that way. Are there any methods you guys have for keeping the plastic from yellowing any further? I'm considering applying a coat of Future over the white parts, but I don't know if that would be effective. Any thoughts?