Been meaning to try this for a while. Removed some tabs to free his arms. Doesn't impact on the transformation thankfully. I need to smooth out the remnants of the shoulder tabs to refine the clearance on the left arm. There's no real reason why they should have been there. I used blue tack to thicken up the shoulder joint as it's loose otherwise. After getting a custom G1 Grimlock years ago and being pleasantly surprised that he could turn his head, because my best friend next door had him when we were kids. The seller told me he just unscrewed the head and cut off a small plastic tab which allowed the head to turn. I tried the same thing with my G1 Sludge and gave him head articulation. Strangely I had a blue ko of Sludge years before who could turn his head. The removal of a small tab under G1 Prime's head allows the same freedom of movement. People complain about the lack of articulation with G1 toys but in the instances I've mentioned, it was down to one or two small, seemingly unnecessary plastic tabs. Anyway I digress. Here's G1 Thunderclash with improved arm movement. "Thunderclash is on the move. Thunderclash is loose!"