You could try that, but it seems that the pulleys were balanced by the manufacturer. At least, the one I have has three 1/4 inch drill marks right together on the rim. I doubt that anything much could happen to such a solid chunk of iron to throw it off balance unless, like Phil says, there is a large piece missing. I suppose that visually it spins without a wobble that could indicate its not being on straight -- right?
Bob S.