G&G GR16 EBB takedown question

[Nox]

I've got a G&G GR16 EBB thats here in the shop that needs to be taken down, and I am having problems taking the silver blowback part out of the runners so I can get the gearbox apart.
I found a post on a forum that says "just take the silver blowback thingy off, it should be easy" but it really isnt all that easy. Its riding in a groove and there's a bend or something locking it in place and since its a customers gun, I'm sure as hell not going to horse on things.
Apparently my normal google fu is failing for how-to searches...so if anyone can help I would greatly appreciate it.
Thank you!