When my relatively new smok 1.5 ohm Dual Coil cartimizers get hard to draw I convert them to 3 ohm by cutting the wire that comes from the center hole and runs over the top and down the side of the carto with wire cutters. I'll put it on a VV/VW device and the draw gets much "looser". This way I extend the life of Dual Coil LR cartomizers that become hard to draw.