You need a 0.05" pin punch, which you can order from Brownells. Be aware that the front blade is a force fit, which will require a vice to remove. The hole in the blade is drilled after installation, so you will never be able to replace the original. In short, do it as a last resort.
The rear blade is easy to remove and replace. The screw is staked, and must be broken to remove it. You will need to modify a screwdriver to install a new one. Notch the tip with a Dremel tool to fit around the screw shaft. Stake the new screw with a center punch when the nut is tight.
There is an extremely tiny spring and plug in the screw head, which serves as a detent inside the hexagonal hole. Watch where they land, you will need them again