you will have to remove the blade assembily from the motor. remove the bottom plate to exspose the 2 fixing screws holding the blades to the motor assem. then strip the blades by removing the fixing screws along the blade. then lift the blades apart carefully, remembering how it came apart so that when you reassemble it in the reverse order. there will be spacers on each bolt,and maybe some tin spacers.
(dont forget to put them back on assem.) if the blades are not cracked, find a flat metal surface and hammer them straight, making sure that you don't dink or crease mark them. look down the blade with your good eye for straightness.if the cutters are bent,(that's the pointy bits),clamp the blade in a vice and tap the cutter until in line with the rest.reassemble in the correct order,making sure that the blades are free enough to move.fit to motor,lubricate with some 3in1 oil. if you have any bit's over you have either rebuilt wrong or you have just made a bad modification