No they don't I've only seen sites from Japan that sell replacement runners.
Doubt it. But if you know what the piece looks like, they have plastic plate. A material that can be cut to shape. They also sell putty, which can be molded to shape your missing part
Well, they do sell high definition hands and weapons, but not exact runners for kits. But no one really does. I don't think bandai even does that, at least not in the US
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