Finally got my replacement left arm from TFSource today.
Here's a close up. See all that blue where it should not be? I wonder if it was a coincidence that was just the arm I got, or it's from a sketchy Rumble TFSource is scavenging from for parts replacement. Whatever, I'm just glad both arms bend the right way now.
Frenzy: "?"
Rumble: "Your problem now."