I replaced my coolant tank and refilled the system, bled it ok and everything seemed fine but when I went to stick the under tray back on the tank was dripping coolant onto the ground. I traced the leak to the junction between the tank and the bottom bracket that holds the bleed screw and the level sensor. Do I have a knackered seal ? Is there a seal? I didn’t notice one on the tank (or the old one) but didn’t check the bottom bracket. It is a very small seep but enough to drip and lose coolant over time. How should the tank be sealed to the bottom bracket?