AEA Problems

To guys that know stuff...
AEA megoladon.58 cal issues.
1) the brass pin that is seated in the clear portion of the magazine keeps falling out .the place where I bought it said they've never seen this issue
2) in the back where the rear tank screws onto on the gun itself inside the rear block,if u will where the valve is loosens up to where I can freely turn it with my fingers .it needs a special tool to tighten properly.

So the first issue I can fix but of course I have to take it apart and press the brass pin back in the cover ..it works for a bit and happens again. But the place I bought it was trying to telle I'm using it wrong which I'm not and just because you've never heard of it doesn't mean it doesn't happen to other ppl since it can be fixed with simple tools so maybe noone bothers to complain if this is your attitude about it .
He wouldn't oblige me sending new mags but instead wants to send me the clear plastic part.

The second issue I was surprised at
I take off the tank after every use
Anyone have these issues