A friend sent me the link last night now I couldn't find it lol.
Basically you unscrew the 3 screws on the grey piece on the upper arm. Only need to mod the white piece, basically to let it clear the red T piece that the shoulder pad is pinned on. The T piece is mis-assemble between the left and right shoulder, but the pin is difficult to remove so swapping is out of the question.
See the pic below. Note the cavity. On the right is before modding. Left is after. Shave about 1.5mm of plastic off
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