I agree with MrFixit, looks like cleaning blade to me.
If it isn't cleaning blade, the other thing it looks like is the mylar by the potential control. You can remove the developer and clean it, but it is a lot easier to clean if you have the AP assembly out.
If it isn't cleaning blade, the other thing it looks like is the mylar by the potential control. You can remove the developer and clean it, but it is a lot easier to clean if you have the AP assembly out.
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