Hi, I've had a problem with my trolley for about 6-12 month an can't work out how to fix, thinking it's down to the pump but once I've got it going it works. Ok I switch it on but water doesn't come out so I unplug hose to DI vessel push hose to floor then water starts to pump through, next problem is water stops pumping through when water container is 2/3 full so I have to keep topping container up an it's killing my back messing about. Container should empty before water stops pumping through. I've had the trolley about 7 year and this is my third pump which I've had for about 2 year, any help I'd be grateful for.