Request Advice on DX VF-25 (V1) Screw Cover

[trojan_gambit]

My DX 25G (V1)'s shoulder balljoint is loose, I want to disassemble it and insert blu-tack to tighten it, but the screw is hidden under the round cover.

I need advice on how to open this screw cover. I'm not sure I can just pry open the screw cover without causing much damage to surrounding part.

Thanks in advance.