The Redeye is a 66-1, and it takes a class 66 round bobbin. If it's got the slide plate (bobbin cover) that's a plus! (They're often missing because people put them on wrong and they fall off)
It's probably just gummed up with old oil, and some work and elbow grease will free it up. If the decals are good, the cabinet is nice, then $99 is a fair price.
(I'd do it, and I'm a tightwad....right Miriam?
)