I've got what seems like a very basic problem but it's taken most of an evening and it's still not solved. I needed to remove my diverter valve from my Ravenheat CSI 120 lox nox combi boiler. It had 3 large nuts which I unscrewed. However putting them back on afterwards has been a nightmare as they are impossible to align properly. I think the nut needs to align to the bottom of the screw thread but the pipe angles make this difficult. I managed to reconnect two nuts but the thread is threatening to break on the third. Any tips?