Kroil is a product that's known to work miracles on frozen screws.
If the pin is missing from the winder, that's a bigger problem - there's nothing there to drive the bobbin. Fortunately, you can buy a bobbin winder assembly on eBay fairly cheap. If worst comes to worse, there's always the separate Deluxe Bobbin Winder that is sold in fabric stores. It has a good reputation for most bobbins, including the class 66.
Good luck!
