Before I take this one back to Screwfix and get my money back, can I just test my understanding?
I assume that the way they are supposed to work is that the lever pumps air into the tank, which then forces the liquid out of the hose?
Only, what's happening with this one (and indeed the old one I threw away) is that the pump is filling with liquid and pumping it straight out of the hose. The manual says to pump it 6 times before use, but it hydraulic locks long before that ...