I changed the inner barrel out of my CYMA ak74u for a longer one that was in one of my M4s, a tiny little rubber piece about the size of a grain of rice fell and i didnt think much of it but now after reassembling it the hop up doesnt work at all. Any answers? This is the first gun i've put some effort into to making better and don't know much about the internals or general construction of aegs but would love some help. -Owen