I have one and when I read your post I looked at mine. You're right, the normal "righty tighty, lefty loosey" didn't work--it's just the opposite. I turned the screw to the right, it loosened, took it out and then lifted the blade out. I took a picture of mine with the screw attached and out. One thing, you have to move the guard out of the way to slide the blade out.
blade out
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The writing on the cutter shows which way to unscrew
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