It should spin fairly easily.
Is it making grinding, or clcking, sounds?
Does it spin one way easier than the other?
They are 30 years old. It could be a sticky or worn out bearing.
If it was disassembled, it could be the bearings are not seated properly in the caps.
Obviously, the wires should not be connected to each other, or an ammeter, while trying to spin it.
G-