Remove the top of the Endura T18E tank, drip the liquid down the inside outer wall. Do not fill above the top of the inner air tube.
Once you have filled the tank section with liquid then replace the top until tight, be sure not to cross thread or over tighten.
To change coil, unscrew the base of the tank to expose old coil, twist the old coil and turn anti clockwise until it detaches from the base. Replace with new one and refill tank. Let the e liquid soak into the coil for 5 min before you switch the device on. This will avoid burning out your coils.