My cordless hedge trimmer blades got dull and needed replacement. In retrospect, for an extra $20 I could have gotten a new trimmer and avoided the hassle of blade replacement. Instructions didn't come with the blade, and I couldn't find anything helpful in a quick Google search.
He are my tips
https://docs.google.com/file/d/0B_kuFlF9ob4GODBLTHBYY2U3aDQ/edit?usp=sharing
