You will need to almost completely remove one of the adjusting screws from one side. Pull it out far enough to get a good gap for the new blade to feed into. There is a spring loaded metal plate across the front that will need to be popped off also. I've not had to do this so I'm not sure if you can do it while leaving the adjuster partially in or not. Then you remove the old one, drop in the new one and put everything back together. The spring loaded plate should just snap back in place.
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