Sniper Hop Up Issues

I bought a sniper from a local shop today (http://www.fcsurplus.ca/shopping/products/468504-airsoft-sniper-bolt-action-mb4408a/) and it seems like the hop-up isn't working. BBs are just rolling out the barrel if I tip it down.

This sniper seems to be using a dial on the underside for the hop up. On the inside of the gun there's a post that sticks up and pushes on the hop up unit on the barrel. It seems like that connection is the issue. Almost like there's not enought pressure or something. Does anyone have any ideas how I can fix this?

This is my second replacement (broken rail on the first, jamming on the second, all three were different models) so I'd rather not have to run across town again to return it a third time.

EDIT: I went back and replaced it with a G&G G960 SV. I had them test fire it and all seems well now. Thanks for all the help