That's a great find at $40! It has some neat features. The slotted thread holes look pretty advanced for the style of machine. The dirt and rust is from neglect, the rest just looks like wear from honest use. I don't think the machine was actively abused anyway. I don't see a top for the case so it would have been natural to grab it by the arm to carry it and the base just shows wear from use. I think it'll clean up quite nicely. It will look good (well used machine good) without repainting but the finish is at the point where I don't think it'll hurt anything if you do repaint it.
Rodney