I'd say you need to cut the cotton shorter, so the ends are just touching the bottom of each side.
I've not got the drop dead 2, but I'd say coils have been pulled into the centre, I'd try putting a 3mm coiling rod or 3mm screw driver in them and try pulling them outwards so more centred with the grub screws, this will help with spit back and get the coils closer to the airflow.
Spit back can sometimes be to low wattage for the coils, upping the wattage means the coils vaporise the liquid quicker stopping spitting.