Rachel,
Gathering from your info and the ebay listing you need the block the light and motor plugs plug into. One wire goes to the wall outlet, and the other wire goes to the foot controller.
You can go the eBay route and buy that used one which will work, or you can go to
Sew-Classic.com {
http://www.shop.sew-classic.com/ } and buy brand new ones for $11.95.
http://www.shop.sew-classic.com/Cord...143-SCE143.htm
Sew-Classic has many many parts and supplies for sewists. They are the go-to place for many of us.
Joe