the 315 prefix is usually for Ryobi products (I don't know how old your router is, that code was used for other tools a while back). Give Ryobi a try, and see if they can provide you with a switch.
Back when I owned my BT3000 table saw, the parts guys at Ryobi were great, and the prices for spare parts were quite reasonable. (once, shipping cost more than the part did)