Darren. There great aye. I've had one for years now and love the thing..
Guys, to get it full put the canisters in the fridge for 40 mins or so or in the esky. I guarantee you it will fill it up as good as new, if not even more. They also do not work so good when the 4 or 9kg is about a third full. But really try cooling the canister.