Editing Palettes

I have a beam palette I created with one kind of fixture. The editor shows the values in the palette for "All Types". Then I created the same kind of beam look with a Mac2K and merged it into the same palette. It reads Except All Mac2000". Now I want to knock out the Mac2Ks framing shutters in that palette. Since I can't seem to edit the palette in an editor, and I don't want to rerecord the palette and lose it in all the cues I've already written, how can I achieve this? Pig + backspace isn't working either, because I can't even edit the palette.
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